Psych 2220 osu final

The effect size value indicates what?

the difference between the standard deviations of the sample mean and the population mean

Sample size does NOT affect:

the effect size

Prof. Khalsa is planning to take a sample from a normally distributed population. A sample of which size would be LEAST likely to follow the normal curve?

5

The proportionate reduction in error is a measure of the:

Amount of variance in the dependent variable explained by the independent variable.

If the standard error of the estimate is zero, the relation between two variables is:

Perfect

Based on research with her patients, Dr. Sabine knows that the correlation coefficient between scores on an anxiety scale and comfort at a social gathering is 0.35. According to guidelines established by Cohen, how could we characterize the strength of this relationship?

Medium

If we take N observations from a population with a normal distribution with mean μ and standard deviation s, how many degrees of freedom does the distribution of the test statistic for inference about μ have?

N-1

Dr. Zahn conducts a study that reveals a positive correlation between annual salary and annual amount of seafood consumed. Based on this information, which statement is false?

Positive correlation means that as salary goes down, so does amount of seafood eaten. Individuals who earn a low salary tend to eat more seafood than individuals who earn a high salary.

Based on the following set of data: X = {15, 2, 20, 18, 6, 30, 1, 3, 4, 22, 25, 10}, first calculate Q1: Next, calculate Q3: Finally, calculate the interquartile range

Q1: 3.5 Q3: 21 IR: 17.5

For which combination of variables might a researcher want to calculate the Spearman correlation coefficient?

any ordinal variables

Which information is NOT included in a violin plot?

average score

The effect size is based on the spread of the distribution of individual scores, rather than the:

distribution of means.

t(8) = 0.84, p > 0.01, the researcher should:

fail to reject the null hypothesis.

Standard error is calculated by dividing the _____ standard deviation by the square root of N.

sample

A standardized test has a population mean of 250 and a standard deviation of 47. If a student earns a z score of -1.00, her raw score would be (round to the nearest 2 decimal places):

203

Daily low temperatures in Columbus, OH in January 2014 were approximately normally distributed with a mean of 15.45 and a standard deviation of 13.70. Temperatures in the top 10.93% of days cause the snow and ice to begin to melt. What is the minimum temperature needed for the thaw to begin? (enter a number only, rounded to the nearest 2 decimal places)

32.30

What is the difference between a line graph and a Pareto chart?

A Pareto chart is a bar graph with the bars ordered from highest (on the left) to lowest (on the right).

What does the acronym JARS stand for?

Journal Article Reporting Standards

On a survey of numbers of friends, scores ranged from 1 to 20. a. What is the full range of data, according to the calculation procedure described in Chapter 2? (state a whole number, without decimals. ex: 1) b. What would the interval size be if we wanted seven intervals? (state as a whole number, without decimals. ex: 1)

a. 20 b. 3

If a z score is positive and you want to find the percentage of scores that falls below that score, you would first look up the z score, find the "% between mean and z" column of the z table, and then:

add 50% to the value in the table.

In an experiment comparing two doses of an antihistamine and two types of diets for their ability to relieve allergy symptoms, the best type of graph for summarizing the results would be a:

bar graph

Clarissa wonders about the strength of association between the length of time that an athlete has been on a team and the athlete's self-reported level of self-confidence (on a numerical scale). To find out, Clarissa will gather data and:

calculate a Pearson correlation coefficient.

Mayim wonders how strong an association there is between the length of time a person has been in a job and the person's self-reported level of job satisfaction (on a numerical scale). To find out, Mayim will gather data and:

calculate a Pearson correlation coefficient.

Coin collectors gathered together 658 dimes and recorded the mint year for each one. To look at the distribution of the variable "year minted," it would be BEST to make a:

histogram

At a sample size of infinity, the t distribution:

is identical to the z distribution

A distribution of means would be more likely to have ________ compared to a distribution of raw scores.

lower variance

The statement "The findings based on a sample of 1000 participants were statistically significant, providing evidence for our hypothesis" would be strengthened by:

measuring effect sizes.

As a measure of variability, calculate the variance for the following set of data: X = {36, 55, 40, 37, 42, 43, 60} Enter the numerator (sum of squares) value. Report your answer rounded to the nearest 2 decimal places (ex: round 1.7896 to 1.79). Enter the denominator. Report your answer as a whole number with no decimals (e.g., "1").

numerator: 507.43 denominator: 7

the standard deviation is inflated by

outliers

A researcher was interested in assessing whether a new medication had negative side affects on reaction time. He performed an experiment on a group of rats. One group of rats received the medication, and the other group of rats did not. He then measured reaction time differences between the two groups on a series of tasks. In this experiment, the dependent variable is:

reaction time.

What is the null hypothesis when testing for significance using the Pearson correlation coefficient?

rho=0

Which item would not be included in the Results section of a report on research where all variables are nominal?

sample standard deviation

Madame Bonalie is interested in studying the relationship between a college student's test scores and the number of hours the student spends watching TV. To depict the data, she should use a:

scatterplot

A researcher investigated the relationship between IQ score and years of education (measured as 1-16). What type of graph should the researcher use to illustrate his findings?

scatterplot because it will show the relationship

The _____ of the correlation coefficient indicates the direction of the correlation, positive or negative.

sign

The statement "It is hypothesized that men and women will differ on reaction time measures" best illustrates a:

two-tailed test.

_____ size indicates how much two populations do NOT overlap.

effect

Which of these coefficients indicates the smallest or weakest correlation?

-0.05 -0.79 0.13 0.43

For a simple linear regression, the standardized regression coefficient (Beta) is:

Equal to the Pearson correlation coefficient

What makes a predictor significant

Sig. value under 0.05 (p value)

A one-tailed z test is used when the study will show that the mean will be higher or lower than that of the:

population

We conduct a t test instead of a z test when we don't know the:

population standard deviation.

Suppose that the time for lab mice to complete a familiar maze usually is distributed with a mean of 95 seconds and a standard deviation of 10 seconds. If the limit placed on a mouse "successfully" navigating the maze is 115 seconds, what proportion of mice will be expected not to be able to finish?

2.3

Suppose a t test statistic is calculated based on a random sample of 19 individuals. What is the critical value tsuch that the distribution has probability 0.01 to the right of t? Please choose the correct answer from the following choices, and then select the submit answer button.

2.552

One condition for inference about a mean states that the population values have a _____ distribution.

normal

To calculate the degrees of freedom in a single-sample t test, a researcher subtracts 1 from the sample size, to account for the:

number of scores that can take on different values if we know a given parameter.

The proportionate reduction in error, r2, is thought to ______ the effect size in a regression equation.

overestimate

Based on the statistical software output, select the appropriate summary in APA format. Scores t=0.578 df=199.00 p=0.564 Note: For the Student t-test, the alternative hypothesis specifies that the mean is different from 100.

t(199) = 0.578, p > 0.05

Which variable might we reasonably expect NOT to have a normal distribution?

the amount of cola in a 12-ounce can

Which of the four items included in the Methods section of a research report is optional, depending on the nature of the study?

the psychometric data for each scale used

The hypothesis that we are trying to support by running an experiment is often called

the research hypothesis

When would a researcher use a z test?

when analyzing data from a single sample, drawn from a population where for the population both and are known

A p level of 0.05 corresponds to a confidence interval of ________%.

95

t(4) = -2.06, p > 0.01, the researcher should:

fail to reject

What should go on the x-axis in a time plot?

the time at which the observation was measured

In a two-tailed study with 9 degrees of freedom and an alpha level of 0.05, what are the cutoffs used on the distribution?

+ or - 2.26

Suppose we are testing H0: μ ≤ 100 versus H1: μ > 100. After calculating our sample mean, we reject the null hypothesis. For which sample mean is this LEAST likely to be an error?

M = 120

Six individuals provide responses to two ratio variables X and Y. The data are X = {14, 55, 31, 9, 44, 25, 20} and Y ={2, 10, 3, 5, 1, 6, 0}. Solve the following (State your answer as a WHOLE number with no decimal point.): ΣY2 =

175

In a comparison of two different weight-loss programs, obese participants were randomly assigned to one of two groups: (1) the soy group, a low-calorie group that ate only soy-based proteins, or (2) the traditional group, a low-calorie group that received 2/3 of their protein from animal products and 1/3 from plant products. One of the dependent measures collected was the amount of body fat loss as a percentage of initial body weight. Summary data from each group based on this variable are listed below: Soy group (treat this as μ1): N = 6, Mean = 2.3, Variance = 0.3 Traditional group (treat this as μ2): N = 6, Mean = 1.223, Variance = 0.251 Calculate Cohen's d as a measure of effect size. Round to the nearest 2 decimal places:

2.05

A standardized test has a population mean of 100 and a standard deviation of 20. Calculate the standard error for a sample of 45 students (round to the nearest 2 decimal places).

2.98

A graph that reports true values but visually distorts the data falls victim to the _____ lie.

inaccurate value

When would a researcher use an independent-samples t test?

when analyzing data from two samples, which each participant belongs to just one

For two independent samples, the upper bound of the confidence interval is calculated using the formula:

(MX − MY)upper = t(sdifference) + (MX − MY)sample.

The critical value of the t statistic for a one-tailed test with N = 7 and a plevel of 0.05 is ________. (enter positive value, with no sign, rounded to 2 decimal places)

1.94

A study of the Consideration of Future Consequences scale indicated a population mean of 3.20 and a standard deviation of 0.70. For a z score of -1.2, the raw score would be (round to the nearest 2 decimal places):

2.36

Given a regression equation with an intercept of 14 and a slope of 4.7, what is the predicted value of Y for an X value of 11?

65.7

A power analysis reveals that the study being run has low power. Which of the following methods is not an appropriate way to increase statistical power?

Increase the variance of the distributions.

Dr. Bartholomew conducts a study that reveals a negative correlation between annual salary and annual amount of fast food consumed. Based on this information, which statement is false?

Individuals who earn a low salary tend to eat relatively little fast food.

Based on the hypothesis test in the previous question, the statistical decision would be:

Reject null, because the r statistic is in the critical region.

t statistic and null

Reject the null hypothesis when the absolute value of the test statistic is greater than the critical value.

Which is NOT considered an aspect of data ethics?

replication of findings

A paired-samples t test is reported as t(300)=2.07, p<0.05, d = 0.67

This is a medium effect, indicating that the difference may be practically important.

test statistic formula

Used to decide whether or not to reject H0 (M-um)/sm

Dr. Ybarra is investigating the link between the number of family dinners and the rate of teenage drug use in a community, with drug use being the outcome variable. The slope of the regression equation is -0.71. The sum of squares for the number of family dinners is 560, and the sum of squares for the rate of teenage drug use is 1450. The standardized regression coefficient for the relationship between family dinners and teenage drug use is:

-0.44

When two variables are not related, they have a correlation coefficient close to _____.

0

Imagine that you are playing darts. Over three days of play, you throw the darts 503 times as you attempt to hit a bullseye. 74 of your attempts hit a bullseye, however, 18 of your attempts miss the dart board entirely. What is the probability, in the long run, of hitting a bullseye or missing the dart board entirely? (report a number rounded to the nearest two decimal places, but not a fraction)

0.18

Data are recorded on a simple random sample of elementary school children. Researchers report a correlation of r = −0.79 between the time spent watching TV (X) and hours spent on homework (Y). Which would be a correct conclusion about this value of r?

A strong negative association exists between time spent watching TV and time spent doing homework.

Where can a researcher go to preregister a research study?

AsPredicted.org

The table includes information for creating a regression equation to predict students' attitude toward statistics from their attitudes toward Britney Spears and beer.

Attitude toward beer

Independent-Samples T-Test tdfpMean DifferenceSE Difference Time t=-2.265 df=6 p=0.064 Md Difference=-27.00 11.922 Researchers were interested in whether there is a difference in the time men and women take to get ready for a date. Use the statistical software output to answer the following question. Assume µ1 represents males in the U.S. and µ2 represents females in the U.S. Based on the output, in regard to the hypothesis of no difference in average time between men and women, you should:

Fail to reject null, because given a true null, the probability of this result is > 0.05.

in a correlation study (relationship) df equals

N-2

In the graph, we investigate the relationship between knee height and total height (both measured in centimeters) for a sample of five men. The only regression parameter for this relationship that can possibly be negative is the ______.

intercept

A Wilcoxon signed-rank test is used only when at least one of the variables is _____.

ordinal

z scores are useful because they:

give us an understanding of where a score falls in relation to the mean of its underlying population, allow comparisons to be made between scores from different distributions, and permit the transformation of z scores into percentiles.

Increasing sample size:

increases the likelihood that we will reject the null hypothesis.

If the cutoff for a one-tailed z test is -1.65, choose which of the following z scores would cause you to fail to reject the null hypothesis. (select the appropriate z score or scores)

2.5 -1.96 -1.99 1.5 -2.3 0 -1.2

When running a single-sample t-test, you should fail to reject the null hypothesis when your test statistic (t) is:

less extreme than your critical value(s).

By increasing statistical power, the probability of making a ________ error is ________.

Type II; decreased

If we reject the null hypothesis, the result is said to be:

statistically significant.

Previous research has found that college students have healthier eating habits, on average, than those who are neither college students nor college graduates. If the population mean for number of times eating breakfast per week is 4.5, with a standard deviation of 1, what is the approximate percentile for a student who eats breakfast 5 times per week? (List your answer as a whole number, with no decimal and no percentage sign.)

67

If the sorority actually had 9 members (still with the same average height), would you expect the percentile value to increase or decrease (compared to your answer in last question) (0.5 points)? Why? Provide a clear and complete explanation for your choice (1 point).

Decrease (0.5 pts) because standard error of the sample average would increase (0.5 pts) with smaller sample size. In turn, z would decrease (0.5 pts), meaning the percentile would be smaller.

In calculating pooled variance, why do we make adjustments for sample size?

Estimates of spread from smaller sample sizes are likely to be less accurate than estimates of spread from larger sample sizes.

Suppose that for a particular study the expected value of a phenomenon is 0.00. The study results in a reported 95% confidence interval of [-0.68, 0.11]. What decision do you make based on the 95% confidence interval?

Fail to reject the null because the population mean is within the confidence interval.

The population mean for a college Introduction to Biology quiz is 20 points. A sample of 35 high school seniors earns an average of 16.53 points. A 99% t confidence interval for the true mean of high school seniors is [13.85, 19.21]. Based on this confidence interval, what would your decision be in regard to a 2-tailed null with an alpha level of 0.01?

Reject the null, because 20 is not in this interval.

Researchers were interested in the effect of extrinsic motivation on task persistence. Two groups of students are brought into the lab, some are given a reward for doing a task they enjoy and others are not given a reward for completing a task they enjoy. The following table shows the number of minutes the students worked on the task. Does giving a reward make a difference in students' task persistence? Summary data are below: No reward (treat this as μ1): N = 5, Mean = 28.2, Variance = 19.7 Reward (treat this as μ2): N = 5, Mean = 22.6, Variance = 9.3 Calculate the 95% confidence interval. List the lower found and upper bound

[0.05,11.15]

The practical use of statistical power is that it informs you the researcher:

how many participants are needed to conduct a study that will produce quality data that you can trust.

What should be done before a study is even started?

Choose an appropriate statistical test.

Ethan once heard that wearing colorful socks helped release your positive energy toward others. Being the scientist that he is, he decided to put the claim to the test by running a well-designed study. He had 18 people wear colorful socks and another 18 people wear white socks. After carefully designing, collecting, and analyzing his data, he found no differences between the groups that he studied. Ethan's findings support which hypothesis?

Null hypothesis

Which equation describes the factors that go into the power of a hypothesis test?

Power = Effect Size Sample Size

In Pearson's r value based on the software output, assuming you wanted to test for a relationship at an alpha level of .05, your decision for the 2-tailed null hypothesis would be to: Correlation Matrix Pearson's r p value ---grade Pearson's r p value 0.788 0.001 ---

Reject the null, since the p value is < 0.05

Which measure of variability is more useful when describing a data set Why is that measure more useful

Standard deviation The value is in the same units as the variable measurement

Using the following set of data (which includes 24 values), construct a single stem-and-leaf plot (select the best representation on the Carmen quiz): 3.5 6.5 4.0 3.5 2.0 2.5 4.5 4.0 3.0 3.5 3.0 3.0 4.0 4.5 2.5 3.5 3.5 3.0 2.5 3.5 3.5 0.5 2.0 1.0

Stem Leaves 0 5 1 0 2 0 0 5 5 5 3 0 0 0 0 5 5 5 5 5 5 5 4 0 0 0 5 5 5 6 5

A researcher has discovered a mathematical mistake in her calculation of the sample mean. The actual mean value should be 10 higher than that originally reported. What will this new sample mean do to the raw means on the distribution?

The raw means should increase by 10.

A study preregistration established a desired sample size of 50, but the final study was based on a sample of size of 63. How should a reader react to this mismatch between the planned and actual sample sizes?

The reader should wonder whether the sample was enlarged in hopes of confirming the research hypothesis.

A researcher develops a testing program and sets the cutoffs at 0.001% in hopes of being able to include a large number of scores while rejecting the null hypothesis. Did this determined cutoff help the researcher?

The researcher cannot control how often the null hypothesis will be rejected.

A researcher planning out a study worries that some data values may be invalid due to problems with how they were collected. What should the researcher do about this issue?

The researcher should have a plan in advance for deciding which values to discard.

Based on the scatterplot, state the direction of the relationship and describe the relationship in terms of the variables for this example. (Downward trend)

The scatterplot depicts a slight negative correlation meaning it has a downward trend. People who have less quality of life also have more negativity. People with a higher quality of life have less negativity. As the y variable decreases as does the x variable. ( Feedback- as y decreases, x increases * -0.25, everything else is correct)

Assume that we find a positive correlation between the number of hours students spend studying for an exam and their grade on the exam. If we calculate the regression equation for these data and find that the yintercept is 65, what conclusion can we draw?

When students do not study at all, we would predict a score of 65 on the exam.

What kind of correlation would you expect to find between the results of two dice thrown simultaneously?

Zero

A researcher conducts a study using an alpha level of 0.10 and a 95% confidence interval. With these parameters, which of the following tests will include a bigger area in the tails if a two-tailed test is performed?

a test with an alpha level of 0.10

A group of 19 students were surveyed and asked to report: How many hours did you sleep last night? How many classes are you currently taking? The graph below was made based on their responses. a) Is a bar graph the best graph to use for the variables shown? (State yes or no) 0.5 points b) Explain your answer to part a (use criteria such as number of variables and scale of measurement to explain your response). 1 point c) State one thing that could be improved for this graph. 0.5 points

a) no -0.5 b) number of classes is scale too -0.5 c) either start x axis at 0 or add a title -0.5

What type of lie is most likely being depicted in the following example: A seventh-grade teacher wanted to examine how effective her teaching was before formal end-of-year evaluations. To do so, she devised her own scale with questions on specific lessons, on her teaching style, and on her effectiveness overall. She used a 6-point scale as follows: 1 = very poor, 2 = neutral, 3 = good, 4 = very good, 5 = excellent, 6 = superior.

biased scale

A(n) _____ lie slants information in a particular way.

biased-scale

Which item in the Results section of a research report is a new-statistics element?

confidence intervals

Wendy is a Weight Watchers group leader. To get a better idea of how to help those she will be working with to achieve their weight-loss goals, she wishes to know the average weight-loss goal of the individuals in her group. What kind of statistic should Wendy use?

descriptive

The United States Department of Homeland Security Threat Advisory System measures threat as severe, high, elevated, guarded, or low. In this system, threat is a ________ variable.

discrete and ordinal

For a negative z score, we:

double the percentage below that z score to get the percentage of scores that are at least as extreme as the z score.

Stem-and-leaf plots offer an advantage over histograms and frequency polygons in that they allow us to:

easily compare two groups of data together.

A graph showing new job growth by month from September 2010 to December 2010 shows a steady increase. A popular news magazine makes the claim that the job outlook is great for the New Year and beyond. This is an example of a(n):

extrapolation lie.

Mr. Abdul gives a math test to a group of high school students. Because of the way he assigns grades, no student will score less than 45, and some may score above 100 by earning extra credit for answers that particularly impress Mr. Abdul. His grading method establishes a(n) _____ effect.

floor

Organizing raw scores into a(n) _____ distribution allows a researcher to see the pattern of responses for a variable.

frequency

Dr. Kirch is a psychiatrist and finds that 70% of his patients qualify as having symptoms of sleep disorders, according to the results of a questionnaire. Dr. Kirch reports that 70% of the population must have the same condition as well. However, this study lacks ________, due to his biased sample.

generalizability

Steve is recording data on reaction times. The scores cover a wide range, and time is being recorded in milliseconds. It would be in Steve's best interest to use a(n) _____ frequency table to visually represent these data.

grouped

Cronbach's alpha is commonly used to estimate:

internal reliability.

A light bulb manufacturer wants to ensure that the mean lifetime of a light bulb is 500 hours. If the testing program illustrates that the mean lifetime of a light bulb is only 125 hours, which is in the critical region, the null hypothesis:

is rejected.

It is important to estimate the population standard deviation from the sample standard deviation because:

it leads to a slightly larger and more accurate standard deviation.

A major limitation of the range as a measure of variability is that:

it will exaggerate the variability if there are outliers in the data set.

Dr. Suzz wants to examine whether the average grade for students in her class, recorded as percentages, changes over the course of the semester, week by week. To graph the data, she should use a(n) _____ graph.

line

The relationship between the number of televisions per capita (X) and average life expectancy of people (Y) in various countries around the world has a strong positive correlation. Because of this, we should:

look for other potential reasons to explain the relationship.

The Lee family is looking to buy a house in one of two suburban areas just outside a major city, and the air quality is a top priority for them. One suburb advertises use of hybrid cars and solar panels, while the other area focuses on its convenient bus routes and availability of Hummer dealerships. Is the mean or median the better measure to use for deciding which area has better air quality? (Hint: both these populations are skewed.)

median, because it is less biased by skewness being dependent on the middle score

Assume a researcher wants to understand usage pattern of buses in Columbus. She passes out a survey on the bus where one question is "Which bus route do you use most often?". The following subset of a larger data set is X = {10, 11, 2, 8, 21, 2, 2, 8, 18, 14, 10}. (NOTE: each number corresponds to a bus route) Pick all measures of central tendency that are appropriate for this data (select one or more):

mode

For which combination of variables are there the greatest variety of ways to analyze the data?

nominal independent variable, scale dependent variable

A lot of equipment fails when still fairly new or quite old, and not a lot of equipment fails when it is only moderately old. What kind of relation would the scatterplot of equipment age and equipment failure rates display?

nonlinear, U-shaped curve

For which combination of variables might a researcher want to calculate the Pearson correlation coefficient?

only scale variables

You can use the z table to look up the _____ of scores between the mean of the distribution and a given zstatistic. Please choose the correct answer from the following choices, and then select the submit answer button.

percentage

Chloe wonders whether college students whose parents are teachers know more about current events than the average college student does. She has a current-events test for which she already knows that, in general, the average score is 64 out of 100, but she does not know the standard deviation. She assembles a sample of students whose parents are teachers and has them take the test. Once she has the scores in hand, Chloe will:

perform a single-sample t test.

A researcher has determined that the population mean does not fall within the raw means of the sample distribution. The researcher concludes that it is not plausible that the sample comes from the _____.

population

A researcher plans to calculate the Cohen's d value for a study that he has just performed. The researcher records the population mean as 6.23 and the sample mean as 4.22. What other value must the researcher include in his calculation for the Cohen's d value?

population standard deviation

If the correlation between two variables is close to 1.0, we can conclude that the:

predictor variable may cause changes in the outcome variable even when the study is observational, but the change may still be due to a confounding variable.

Which measure of variability is not affected by outliers?

range, variance, standard deviation

Number of children per household on the US Census is an example of which kind of variable?

ratio

When a report includes psychometric data for each scale used, what does that refer to?

reliability and validity information

If a researcher has found a Cohen's d value of 1.2, this study is considered to have a large effect. This illustrates that the study has a large difference in the:

sample mean and the population mean as reported in the standard deviations.

The only practical difference between conducting a z test with a z distribution and conducting a t test with a tdistribution is estimating the:

standard deviation

To find the percentage of scores above a z score of 1, you would look up the z score in the z table and find the value in the "% between mean and z" column. Then you would:

subtract that value from 50%.

Which distribution has a greater spread?

t Because σ is unknown and we use s to estimate it, there is greater variation in the t distributions.

Unnithan, Houser, and Fernhall (2006) were interested in whether playing the game Dance Dance Revolution (DDR) met the American College of Sports Medicine recommendations for exercise to improve cardiovascular health. Twenty-two adolescents, 10 of whom were classified as overweight and 12 of whom were not overweight, played DDR for 12 minutes. During the 12 minutes, the researchers measured each participant's heart rate. On average, the researchers found no difference between the heart rates of the two groups. Both groups' heart rates were above the minimum recommended for cardiovascular exercise. What is the sample in this study?

the 22 adolescents who participated in the study

For a simple linear regression, what does the standard error of the estimate represent?

the average deviation of each individual score from the regression line

What is one of the two main pieces of information included in the preregistration of a study?

the data analysis plan

When specifying the null and research hypotheses for an independent-samples t test:

the research hypothesis posits a difference between population means.

Two graduate students who are interested in whether a new technique for teaching long division is better than the usual technique get permission to conduct a study at a local elementary school. Half of the fourth-grade students are assigned to Ms. Steener, who teaches them using the new technique, and the remaining half are assigned to Ms. Cadwaller, who teaches them using the usual technique. After the lessons, all students complete the same exam to test their long division skills. Which two are confounded?

the teaching techniques and the teachers

If the symbol = is found in the null hypothesis, we declare the test to be _____-sided.

two

Bayesian thinking leads to different conclusions based on:

two different priors.

The normal curve is _____ and _____.

unimodal; symmetric

Mark is looking at a histogram depicting years of education. In looking at the histogram, the x-axis most likely represents the ________ while the y-axis most likely represents the ________.

values of the variable "years of education"; frequencies or number of people

Including a dependent variable that is NOT a scale variable _____ of the paired-samples t test, but does not preclude use of this test, because the paired-samples t test is a robust hypothesis test.

violates one of the assumptions

If a researcher rejects the null hypothesis based on the results of a paired-samples t test, to draw the same conclusion based on the confidence interval:

zero cannot fall within the bounds of the confidence interval.

Consider a population of scores for which the mean is 61.1 and the standard deviation is 8.9. Given a raw score of 60.3, what is the z score? Please choose the correct answer from the following choices, and then select the submit answer button.

-0.09

Researchers are interested in the potential of famotidine as a potential new drug to be used in the treatment of schizophrenia and assess the drug's effectiveness by testing people with a schizophrenia measure in which lower scores indicate less symptoms of schizophrenia. Assume it is known that the population mean of this measure is 35.50. In a trial of the drug, 121 individuals had a mean of 34.30, with a standard deviation of 5.10. Calculate Cohen's d as a measure of effect size of the new drug. Round your final answer to the nearest 2 decimal places.

-0.24

A study of the Consideration of Future Consequences scale indicated a population mean of 3.20 and a standard deviation of 0.70. For a CFC score of 3.0, the z score would be (round to the nearest 2 decimal places):

-0.29

A standardized test has a population mean of 250 and a standard deviation of 47. If a student earns a raw score of 199, her z score would be (round to the nearest 2 decimal places):

-1.09

Calculate Cohen's d as a measure of effect size for the following paired samples data: (calculate the difference scores as D = Xafter - Xbefore and pay attention to sign!) Participant. Before After Intervention Intervention 1 200 180 2 185 167 3 270 225 4 205 199 5 170 155

-1.43

What is the effect size for a paired-samples t test where the mean of the 11 difference scores is -11.2 and the estimated population standard deviation is 7.28?

-1.54

After extensive measurements of the time necessary to complete the first homework assignment, a teacher determines that there is a population mean of 100 and a stardard deviation of 20. If she samples a class of 60 students and calculates a mean of 96 minutes, what is the z statistic (round to the nearest 2 decimal places, don't forget a negative sign if necessary)?

-1.55

Researchers who study the process of reading in children have discovered that better readers make smoother eye movements across the page (i.e., there is a positive correlation between reading skill and the smoothness of the eye movements). Which of the following statements is a possible cause of the correlation between smooth eye movements and reading ability?

The ability to make smooth eye movements improves reading ability. Having good reading skills allows a child to make smooth eye movements. Some third factor might cause both smooth eye movements and improved reading ability. All of these options are possible causes of the correlation.

After calculating a paired-samples t test, given a two-tailed test, an alpha level of 0.10, and 12 degrees of freedom, the critical values for t have an absolute value of: Please choose the correct answer from the following choices, and then select the submit answer button.

1.782

Spotify, a music streaming service, wants to know if individuals who listen to the "Power Workout" playlist during their workouts burn more calories than the average person. Suppose that during an average workout, the average person burns 355 calories. Spotify samples 36 people (N=36) who listen to their playlist and find that they burned a mean of 410 calories, with a variance (s2) of 29,700. Caculate the t statistic. Round your answer to the nearest TWO decimal places.

1.91

The critical values of the t statistic for a two-tailed test with N = 101 and a plevel of 0.05 are ________. (enter positive value only, with no sign, rounded to 2 decimal places)

1.98

Assume that a population is normally distributed. Which sample size is MOST likely to be normally distributed?

1000

Given a regression equation with an intercept of 134 and a slope of -1.92, what is the predicted value of Y for an X value of 12?

111

For a set of 6 numbers, standard deviation = 11. For this data, variance = (enter as a whole number with no decimals)

121

Previous research has found that college students have healthier eating habits, on average, than those who are neither college students nor college graduates. If the population mean for number of times eating breakfast per week is 4.5, with a standard deviation of 1, what is the approximate percentage of students who eat breakfast more than 5 times a week? (List your answer as a whole number, with no decimal and no percentage sign.)

33

A group of at-risk children have the following reading comprehension scores: 30, 35, 33, 32, 34. The test mean is 50 with a standard deviation of 5, so these scores are considered extremely low. After a delay of one year, the students are tested again. Which data set would be most likely if their scores had regressed to the mean?

35, 40, 34, 40, 42

Consider a study testing the hypothesis that, on average, individuals will remember more words in a recall memory test when they are given a new cognitive enhancement drug than when they are given a placebo. The following scores, measuring the number of words remembered, are provided for five individuals tested in both conditions. Drug condition: 7, 9, 8, 9, 8 Placebo condition: 5, 7, 6, 8, 9 The sum of squares, SS, needed to complete the final calculation of the paired-samples t test, is _____. (Answer using two decimal places.)

6.80

Credit card companies will often call cardholders if the pattern of use indicates that the card might have been stolen. Let's say you charge an average of $450 a month on your credit card, with a standard deviation of $90. The credit card company will call you anytime your purchases for the month exceed the 98th percentile. What is the dollar amount beyond which you'll get a call from your credit card company? (Enter the dollar amount rounded to the nearest whole number, with no decimal point and no dollar sign)

630

Based on the SPSS output calculate the predicted Final Exam grade for a student who has a Homework grade of 80 and a Midterm grade of 84. Enter your answer rounded to the nearest TWO decimal places.

84.35 y= 6.851+0.114 (80) + 0.814 (84)

Six individuals provide responses to two ratio variables X and Y. The data are X = {14, 55, 31, 9, 44, 25, 20} and Y ={2, 10, 3, 5, 1, 6, 0}. Solve the following (State your answer as a WHOLE number with no decimal point.): ∑(XY) =

910

Another teacher decides to average the height of all 15-year-old male students in his classes throughout the day. By the end of the day, he measured the height of 57 boys and calculated an average of 68.1 inches. The known mean height for 15-year-old boys is 67 inches, with a standard deviation of 3.19 inches. What is the percentile rank for this sample? (enter a number only, rounded to the nearest 2 decimal places)

99.53

Data are collected on daily ice cream sales at the dairy bar on a university campus and daily reports of the number of students having flu-like symptoms at the university health center. Ice cream sales and number of students having flu-like symptoms are found to be highly negatively correlated. What does this tell us?

A confounding variable, such as temperature, links these two variables.

Which statement about correlation is true?

Both −1.00 and 0 are perfect correlations. Correlation always implies causation. Correlations only provide clues to causality. Correlation is used to test for causality.

Why does random assignment help control for confounding variables?

By randomly assigning people to groups, individual differences that may influence the dependent variable are randomly distributed throughout the conditions, rather than being systematically related to the independent variable.

Janel conducts a study to examine whether students' performances on the first quiz in each of two classes taken in the first term of their freshman year are correlated. The scores, out of 100, are provided for nine individuals who are attending both classes. Class 1: 87, 78, 87, 85, 93, 98, 83, 82, 73 Class 2: 87, 86, 92, 90, 90, 91, 89, 78, 76 Knowing that r = 0.72, Janel calculates the proportionate reduction in error. Based on the value of the proportionate reduction in error, which statement is true?

By using the regression equation versus using the mean to predict Y, Janel reduces 51.84% of the original error.

Nomi is interested in the connection between mental health and time spent in nature. Previously he had studied a group of 4-year-olds to determine the average number of hours they spent outside in nature. Now he collects depression scores from those same individuals when they are age 30. He graphs his data on a scatterplot (higher scores indicate a higher likelihood of depression). Using the A-B-C model, which is NOT a possible explanation for the data?

Children who have a predisposition for depression are more likely to spend time alone outside.

A consumer advocate is interested in evaluating the claim that a new granola cereal contains 4 ounces of cashews in every bag. The advocate recognizes that amounts of cashews will vary slightly from bag to bag, but she suspects that the mean amount of cashews per bag is less than 4 ounces. To check the claim, the advocate purchases a random sample of 40 bags of cereal and calculates a sample mean of 3.68 ounces of cashews. For testing H0: μ = 4 versus H1: μ < 4, she decides to use an alpha level of 0.01. Which of the following interpretations of this alpha level is correct?

The alpha level is the probability of observing a sample mean less than or equal to 3.68 ounces, assuming that the true mean amount of cashews per box is 4 ounces or greater.

Dr. Williams conducts a study that reveals a positive correlation between annual salary and annual amount of seafood consumed. Based on this information, which statement is false?

The correlation coefficient is less than 0.

Consider two studies examining the effects of a new drug on the number of words that participants recall in a memory test. Given the information provided, which statement is true?

The effect sizes for the two studies are equal in magnitude and both are considered medium; neither sample size nor the sign of d matters for interpreting effect size.

If a journal awards an article an Open Materials badge, what does this indicate?

The researchers made their experimental methods available, for easier replication.

Dr. Lambert believes that spending time with children increases happiness levels. He asks 10 adults without children to report the average number of hours they spend with children each week. He also has each adult take a Global Happiness Inventory, after which he makes a scatterplot of the data. Using the A-B-C model, which is NOT a possible explanation for the data?

Happier people are less likely to want to be with children.

A researcher is worried that performance on an aptitude test will improve simply because of repeat exposure to the instrument, which will cloud his ability to assess the impact of two unique educational interventions he wants to study (Program A and Program B). Which of the following design options includes counterbalancing?

He could vary the order of the educational interventions such that half of the participants experience Program A first and the other half experience Program B first.

How do histograms differ from bar graphs?

Histograms are typically used to depict scale data, but bar graphs are typically used to depict nominal or ordinal data.

For the following example, select the symbolic version of the null hypothesis: A student wonders if grades in a class are in any way related to where a student sits in the classroom. In particular, do students who sit in the front row get better grades, on average, than the general population of students?

Ho: μ(front_row_students) ≤ μ(general_pop_students)

For the following example, select the symbolic version of the null hypothesis: Cell phones are everywhere, and we are now available by phone almost all of the time. Does this translate into a change of the closeness of our long-distance relationships?

Ho: μ(with_cellphones) = μ(without_cellphones)

What is the very first step in choosing the appropriate statistical test in a study?

Identify any independent and dependent variables.

Researchers are interested in depressed individuals who are not responding to treatment. For their study, the researchers sample 18 patients from their own private clinics whose depression had not responded to treatment. Half received one intravenous dose of ketamine, a hypothesized quick fix for depression; half received one intravenous dose of placebo. Far more of the patients who received ketamine improved, as measured by the Hamilton Depression Rating Scale, usually in less than 2 hours, than patients on placebo. Would random assignment be possible to use? Why or why not? (*Be sure to thoroughly explain your choice.)

In a random assignment, there has to be an equal chance of being assigned to any level of the independent variable (being the use of ketamine or placebo in the participants). In this case, random assignment would be possible because you are able to randomly assign participants who all suffer from the same disorder into a group randomly. The researcher could randomly assign each participant a number that dictates what group they belong in (they would have to use a random number generator to ensure that it is a random assignment and there is no unconscious order he assigned the participants in)

Dr. Thackeray conducts a study that reveals a positive correlation between annual salary and annual amount of organic food consumed. Based on this information, which statement is false?

Individuals who eat a lot of organic food tend to earn lower salaries than those who eat little organic food.

Dr. Fawn conducts a study showing that the correlation between grade point average (GPA) and number of hours of studying per week is 0.47. Based on this information, which statement is true?

Individuals who have low GPAs tend to study less per week than individuals who have high GPAs. Challenge

In 1-2 sentences explain why the following statement is TRUE: It becomes progressively easier to declare statistical significance as we increase sample size.

It becomes easier to declare statistical significance as we increase sample size because increasing the sample size decreases the standard error of the mean, while also increasing the statistical power and makes it easier to reject the null. Rejecting the null makes a test significant.

With which p-level, 0.05 or 0.01, is it easiest to reject the null hypothesis, and why?

It is easier to reject the null hypothesis at the 0.05 level, because it has a larger critical region.

Some cognitive neuroscience researchers were interested in the stability of Blood-Oxygenated Level Dependent (BOLD) signal changes in supplementary motor areas (SMA) of the brain during a motor task performed in a functional imaging experiment. For this exercise suppose the researchers have so much data that their findings represent population parameters. The researchers found that signal change of the SMA has mean of 1.10 and standard deviation of 0.80. On another day they resampled 25 participants and found the group had a mean signal change of 1.29. To understand if this resampled group would be representative, calculate a 95% confidence interval. List the lower bound (rounded to 2 decimal places): and the upper bound (rounded to 2 decimal places):

LB: 0.98 UB: 1.60

Suppose that the known TV viewing habits for a certain state have a mean of 4.7 hours, with a standard deviation of 1.5 hours. A small farming town in the state believes that they have a different mean number of TV viewing hours. A sample of 82 people from this town is used and the mean of 3.9 viewing hours is obtained. Calculate an 80% confidence interval. List the lower bound (rounded to 2 decimal places): and the upper bound (rounded to 2 decimal places):

LB: 3.69 UB: 4.11

Imagine that a study of memory and aging finds that younger participants correctly recall 55% of studied words, older participants correctly recall 42% of studied words, and the size of this effect is Cohen's d = 1.5. According to Cohen's conventions for interpreting d, this effect is:

Large

19 subjects take part in a math exam, followed by an intervention and a post-test. From their pre-test/post-test difference scores, there was a mean difference of 13.19, with a standard deviation of 22.3. Calculate the 95% confidence interval of the difference. Round your final answer to TWO decimal places.

Lower Bound: 2.43 Upper Bound: 23.94

Let's assume that the average NBA basketball player is 79 inches tall. We study 36 NBA bigs and find that their average height is 81 inches with a standard deviation of 1.5 inches. What is the 95% confidence interval for this single-sample t test (for your FINAL answers, round to the nearest TWO decimal places).

Lower Bound: 80.49 Upper Bound: 81.51

Dr. Bartholomew conducts a study that reveals a negative correlation between annual salary and annual amount of fast food consumed. Based on this information, which statement is false?

Negative correlation means that as amount of fast food eaten goes up, salary goes down. Individuals who earn a low salary tend to eat relatively little fast food.

A researcher examines the relationship between an individual's adjustment to becoming a parent and his/her age, while removing the influence of financial status. What procedure would allow such an analysis?

Partial correlation

Professor Bodoni believes that reading makes people more inquisitive. She measures the number of questions asked by six students in a third-grade class over the course of one week. She asks each student to report how much time was spent reading outside of school that week and then makes a scatterplot of the data. Using the A-B-C model, which is NOT a possible explanation for the data?

Reading makes students feel as if they have the answers, so they do not need to ask questions.

Independent-Samples T-Test Grade t=-3.192 df=28 p=0.003 Mean Difference=-8.098 SE Difference=2.537 Based on the statistical software output, select the appropriate decision and APA summary.

Reject null, t(28) = -3.192, p = 0.003

Assume for a given study that the null hypothesis asserts the expected value of a phenomenon is 10. A research study results in a 95% confidence interval reported as [7.142, 9.865]. What decision would you make based on this confidence interval?

Reject the null hypothesis.

Based on research with her patients, Dr. Sabine knows that the correlation coefficient between scores on an anxiety scale and comfort at a social gathering is 0.35. If the critical value for r is 0.330, what would you conclude?

Scores on the anxiety scale are significantly related to feelings of comfort in a social gathering.

The supervisor of a trout hatchery needs to measure the length of a particular species every week after hatching to track their growth. She randomly selects 100 fish from among those that hatched 5 weeks ago and measures their individual lengths in inches. A histogram shows that these lengths have a roughly normal distribution. The supervisor calculates the 95% confidence interval to be 10.2 ± 1.7 inches. What can she say based on this result?

She is 95% confident that the true mean length of this species after 5 weeks of life is between 8.5 and 11.9 inches.

After analyzing a large database, researchers found a statistically significant relationship between consumption of breakfast cereal per day and daily spending on pet care. If this relationship is only due to random chance it would be considered a:

Spurious correlation

A researcher conducts a single-sample t test and finds statistical significance at the 0.01 level. The effect size is then calculated and found to be 0.50. What might you conclude about the findings?

The results are both statistically and practically significant in this case, as the effect size indicates a medium effect, and the 0.01 level of significance is rather impressive.

What is a possible drawback of the big data approach to research?

The sheer number of possible combinations of variables makes it too easy to find correlations.

Dr. Hurt designs a new test to assess depression in high school students and determines that it has a coefficient alpha of 0.97. Based on this information, which statement is true?

The test has sufficient internal consistency to be used as a diagnostic tool.

Suppose we compute the standard deviation of weekly assessment scores and find that it is equal to 1.50. Explain what this standard deviation value means.

The typical quiz score deviates from the average quiz score by 1.50 points. We don't know if the standard deviation is large or small since we don't know the total number of points (would be a large standard deviation if the total number of points were 3, but not if it were 100)

A researcher is interested in how cohabitation before marriage might relate to eventual divorce rates. Specifically, she is interested in whether or not there is a difference in eventual divorce rates between couples who lived together before marriage compared to couples who did not live together before marriage. Any difference found between these groups would be of interest to the researcher, as well as to the popular media. Which of the following is an appropriate research hypothesis for this research?

There is a difference in divorce rates between those who cohabitate and those who do not.

Data from the 1993 World Almanac and Book of Facts were used to predict the life expectancy for men in a country from the life expectancy of women in the country. The resulting regression equation was Ŷ = 9.32 + 0.79(X). This regression equation implies that:

When a woman's life expectancy increases by 1 year, a man's life expectancy increases by 0.79 of a year.

Which statement is true?

When calculating a confidence interval using a z distribution, the z score is multiplied by the standard error to calculate each bound

In a reanalysis of published studies, Twenge and Im (2007) found that for the time period 1958-2001, the need for social approval of people in the United States was negatively correlated with the U.S. divorce rate during the same period (the correlation coefficient was -0.38). This correlation means that:

When the need for social approval was high, divorce rates were low.

The formula used to convert the z score into a raw score is:

X = z(σ) + μ.

How to write Y-hat equation with multiple variables

Y-hat= Constant (intercept)+ variable 1 B (unstandardized coefficients) + variable 2 B

A group of researchers wanted to know if there was a difference in the average yearly income taxes paid by the residents of two very large cities in the midwestern United States. The average for the first city was $6505, and that for the second city was $6511. This difference yields to a z statistic of 2.03. Would these results usually be judged as statistically significant?

Yes, because the z statistic is above the critical value.

strongest correlation

closest to 1 or -1

Effect size, _____, and meta-analysis are included in the new statistics.

confidence interval

Geneva believes she is allergic to cats. She has always avoided them and feels ill when she notices one is around. Katarina does not believe Geneva is actually allergic to cats since Geneva seems to have no reaction to the kitten Katarina has secretly been hiding in her room in their shared apartment. Maybe Geneva is remembering the times when she did not feel well and there were cats present and is forgetting the times she has been around cats and felt fine, a phenomenon also known as:

confirmation bias.

As part of their work in a research methods class, a group of psychology students devised a survey to assess the relation between stress and health. Each member of the class administered the survey to 10 friends, and the data were then pooled. What method of sampling was used?

convenience sampling

For the following example, state whether the trials are independent or dependent. 9-year-old Lucy gets to pick from the candy bag, filled with colored jelly beans, every time she helps around the house. She has been picking (and eating!) candy for 5 days in a row and each time she has picked a different color jelly bean. (Note: The candy bag was only filled one time and no more candy has been added since then.)

dependent

When a frequency table reports frequencies as percentages, what do the percentages represent?

each score's frequency divided by the total number of observations

In 1976, The Complete CB Handbook stated that based on the ever-increasing popularity of CB radios, everyone would eventually learn how to use them in elementary school. The Complete CB Handbookcommitted the _____ lie.

extrapolation

After conducting an independent-samples t test, if the test statistic is greater than the lower cutoff and less than the upper cutoff, the researcher should _____ the null hypothesis.

fail to reject

We calculate a statistical power and find that it is 0.65. This means that if the null hypothesis is ________, we have a ________% chance of rejecting the null hypothesis.

false; 65

Eleazar would like to use voters' ages to predict their reported level of confidence in the political process (on a numerical scale). To do this, Eleazar will gather data and:

find a regression equation.

A(n) _____ is used for plotting frequencies of one scale variable.

histogram

HARKing blurs the distinction between:

hypothesis confirmation and simple data exploration.

Omar is interested in examining symptoms that are related to different anxiety disorders. Because he cannot possibly collect data from everyone who is diagnosed with an anxiety disorder, he recruits a sample of 200 participants from 40 local clinics. To draw conclusions about all individuals diagnosed with an anxiety disorder, he will need to use:

hypothesis testing.

To test whether a chemical found in many common plastic items is toxic, researchers fed different amounts of the chemical (from 0 to 20 micrograms) to mice and later performed a blood test to determine the amount of toxins present in each mouse. To create a scatterplot of the data, which variable should be listed on the x-axis?

independent variable, which is the amount of the chemical given to the mice

Dr. Clarendon studies verbal memory. In one study, she reads participants a list of 20 words and then has them complete a worksheet of math problems. After 2 minutes, she asks the participants to recall as many words from the list as they can; she finds that, on average, they remember 15 words. Based on this information, she predicts that the population would respond the same way. Thus the number 15 represents a(n):

inferential statistic

Dr. Richardson believes that spending time with children increases happiness levels. He asks 10 adults without children to report the average number of hours they spend with children each week. He also has each adult take a Global Happiness Inventory. The correlation between his variables is +0.69. Using a two-tailed hypothesis test and a significance level of 0.05, is the correlation coefficient significantly different from no correlation?

Yes. It is a significant correlation because the correlation coefficient is larger than the critical value of 0.632.

Aaron and Dana train 20 hamsters to press a lever to receive food pellets. For 10 hamsters, the room temperature is held constant at 70°F; for the remaining 10 hamsters, the temperature is held at 85°F. Eighty percent of the 70°F group press the lever more than once per second in each hour-long session. Fifty percent of the 85°F group press the lever more than once per second. Aaron and Dana estimate that 80% of all hamsters trained on this task in a 70°F environment would press the lever more than once per second. Based on the information provided, 80% is a(n):

inferential statistic.

An experiment on the effectiveness of ginkgo biloba in boosting memory function randomly assigned half the subjects to ginkgo and the other half to a placebo. At the end of the study, a 95% confidence interval for the difference in mean scores (ginkgo, control) on a memory function test is [−2.34, 4.39]. Based on this information, we can conclude that if the study were to be conducted many times, 95% of the time the mean difference score would be _____ the confidence interval.

inside

Martin looks at a graph showing that a bakery sold 30 dozen doughnuts on Friday morning and sold 50 dozen doughnuts on Sunday morning. Based on these data, he estimates that the bakery sold 40 dozen doughnuts on Saturday morning. To which statistical error has Martin fallen prey?

interpolation lie

Jim and Pam are conducting an experiment to determine whether temperature influences learning. They train different groups of rats to press a lever to receive food pellets. Each day, they record the ambient temperature in the room to the nearest degree and the number of responses per minute in each hour-long session. In this example, temperature is a(n) _____ variable.

interval

Maria wants to predict salary from IQ; she should use a(n) _____ graph to plot the data.

line

When conducting a paired-samples t test, the comparison distribution is a distribution of:

mean difference scores.

A file drawer analysis is a statistical calculation of the number of studies with null results that would have to exist so that a mean effect size is:

no longer statistically significant.

What kind of study can safely get away with a small sample?

one with a large estimate for Cohen's d

Some researchers suggest that placing a pro-environmental sticker (e.g. "These come from trees") on towel dispensers can reduce paper waste. Average daily paper waste is measured before and after placing the sticker. The question of interest is: Do pro-environmental stickers reduce paper waste? Select the appropriate 1-tailed null hypothesis:

μafter ≥ μbefore

When we choose to use a paired-samples design, we do so because the parameter of interest is _____ the responses between the two groups receiving the treatments.

μdiff, the population mean difference for

Most tests that give IQ scores are designed to have a mean of 100 and a standard deviation of 15. IQ testing is one way in which people are categorized as having different levels of intellectual disability (the category formerly known as mental retardation). Prior to DSM-V, when the term mental retardation was used, four categories were distinguished. Two of those categories are shown below: -IQ of 20-35 (in combination with impaired life skills): severemental retardation -IQ of 50-70 (in combination with impaired life skills): mild mental retardation People with scores above 70 were not considered to have mental retardation. The IQ test was used first, and then, if a person's score fell into the range for mental retardation (70 or below) above, that person would be assessed for life skill impairments. What percentage of people would be expected to have IQ scores that might put them into the severe mental retardation range? Assume that IQ scores are normally distributed in the population. (Enter a number without the percent sign, rounded to the nearest 2 decimal places)

0

If the cutoffs for a z test are -1.96 and 1.96, choose which of the following z scores would cause you to fail to reject the null hypothesis. (select the appropriate z score or scores)

0 -1.99 1.76 -2.3 1.5 2.5 -1.65

Given a regression equation with an intercept of -17.4 and a slope of 1.74, what is the predicted value of Yfor an X value of 10?

0.00

Imagine that you are playing darts. Over three days of play, you throw the darts 503 times as you attempt to hit a bullseye. 74 of your attempts hit a bullseye, however, 18 of your attempts miss the dart board entirely. What is the probability, in the long run, of missing the dart board entirely? (report a number rounded to the nearest two decimal places, but not a fraction)

0.04

Scores on the Wechsler Intelligence Scales for Children are standardized to have a mean of 100 and a standard deviation of 10. A sample of 99 students participated in an intervention meant to boost their scores on the test. The sample is found to have a mean of 102. Calculate the effect size (round to the nearest 2 decimal places):

0.20

Consider a study testing the hypothesis that, on average, individuals who take a new drug will remember more words in a recall memory test than those given a placebo. The following scores, which measure the number of words remembered, are provided for individuals in each group. Drug Group: 7, 9, 8, 10, 8 Placebo Group: 6, 7, 6, 8, 9, 7 Assume that the conditions for an independent-samples t test are met. Given s2pooled = 1.337, what is the variance version of standard error for the Placebo Group needed to complete the final calculation?

0.22

You are playing with a standard deck of 52 playing cards. Each time you draw one card from the deck, and then you put the card back, and reshuffle the deck before choosing another card. What is the probability of selecting a number less than (but not including) 4? Count aces as equal to 1. (report a number rounded to the nearest two decimal places, but not a fraction)

0.23

What is the area between z = 0.50 and z = 1.5?

0.2417 To calculate the area between the two scores, subtract the area from the mean to the z score.

Suppose you wanted to examine the link between number of hours spent watching college basketball games prior to the NCAA tournament and number of correct picks made in the March Madness brackets. Hypothetical data for a group of 10 people is presented below. Hours 47.63 23.5 1.2 56.89 12.44 18.77 42.98 16.89 39.67 5.29 Correct picks 44 27 22 28 27 45 30 25 29 26 Given that SShours = 3263.80 and SScorrect picks = 548.10, calculate the correlation coefficient (round to TWO decimal places)

0.37

If the z score is 1.96, what percentage of scores falls between that z score and the mean?

0.475

What percentage of scores is above the z score of 2.5?

0.62

To determine the profits realized by retail stores and wholesale stores in a city, a sample of 15 stores is considered. The 95% confidence interval is found to be [1.20, 2.48], and the sample mean is 1.84. What is the margin of error?

0.64

Statistical power for conducting a study is typically set at a minimum of:

0.80

The error associated with using the mean for the prediction of weight is 583.33. Calculate the proportionate reduction of error. Jorge is just learning about regression and wants to see if he can use it to predict a person's weight from that person's height. His calculated regression equation is Y = -71.161 + 3.161(X), and his data are listed in the table.

0.94

Dr. Arroz is interested in the relationship between the number of sunny days per year in a city and the happiness of its residents. She calculates the slope as 1.63. The sum of squares for the number of sunny days is 155, and the sum of squares for the happiness rating is 450. The standardized regression coefficient for the relationship between sunny days and happiness is:

0.96

points closer to best fit line

1 or -1

In 1993, the variables of Life Expectancy and People per Television were measured in 5 countries and the data is presented below. Country Life Expectancy People/TV Bangladesh 53.5 315 Kenya 61.0 96 North Korea 70.0 90 United States 75.5 1 Italy 78.5 4 1) Calculate the Pearson correlation coefficient (r) for these variables (round to the nearest TWO decimal places). 2) State the critical value for a two-tailed hypothesis test (alpha = 0.05) (round to the nearest TWO decimal places).

1) -0.92 2) 0.88

Students were asked to rank their admiration of Jennifer Lopez and Venus Williams on a scale of 1 (low) to 7 (high). The population mean rating for Lopez was a 3.72, with a standard deviation of 1.90. The population mean rating for Williams was 4.58, with a standard deviation of 1.46. Another student, Jasjit, rated her admiration of Lopez at a 5 and Williams at a 6. 1) Calculate Jasjit's z score for her rating of Lopez (round to the nearest 2 decimal places). 2)Calculate Jasjit's z score for her rating of Williams (round to the nearest 2 decimal places). 3)Compared to the other students in this database, which celebrity does Jasjit most admire (based on the z scores above)? Enter either "Lopez" or "Williams" as your answer.

1) .67 2) .97 3) Williams

Dr. Hobbes is interested in how her students compare to the population on a standardized language test. She collects the scores of her 16 students. The average for her students is 85 out of 100, with a standard deviation of 6.5. She knows the population mean is 82. What is the standard error?

1.65

Is it harder to get into graduate programs in psychology or history? Five institutions in the U.S. were randomly selected from among all institutions wth graduate programs. The first number for each is the minimum grade point average (GPA) for applicants to the psychology doctoral program, and the second is for applicants to the history doctoral program. Wayne State University: 3.0, 2.75 University of Iowa: 3.0, 3.0 University of Nevada, Reno: 3.0, 2.75 George Washington University: 3.0, 3.0 University of Wyoming: 3.0, 3.0 Perform a two-tailed hypothesis test, with an alpha level of 0.05. Calculate the differences scores as D = Xpsy_gpa - Xhistory_gpa 1) Calculate the standard error of the difference: (round your answer to the nearest TWO decimal places) 2) Calculate the t-statistic: (round your answer to the nearest TWO decimal places) 3) Based on the hypothesis test in the last question, you would decide to:

1) 0.06 2) 1.64 3) Fail to reject null, because the t statistic is NOT in the critical region.

Does the average salary of third basemen differ from that of shortstops? Five third basemen and five shortstops were selected at random from the National League. Their 2005 season salaries (in millions of dollars) were calculated and summary data are listed below: 3rd basemen (treat this as μ1): Mean = 1.113, Variance = 1.263 Shortstop players (treat this as μ2): Mean = 1.958, Variance = 4.379 1)Calculate the standard error (sdiff). Round to the nearest 2 decimal places: 2)Calculate the t-statistic. Round to the nearest 2 decimal places:

1) 1.06 2)-0.80

In a fictional study, the influence of a television program on children's aggressiveness was examined. The number of aggressive responses was measured during an observation period after viewing the television program to see if the average responses were any different than the national average without watching TV. Assume that the known national average for number of aggressive responses typically performed by children who do not watch television is 6.647. Participant's aggression scores after viewing the TV show were: 9, 3, 11, 12, 14, 6, 12 To test the null hypothesis, 1)calculate the t statistic (step 5). Round your final answer to TWO decimal places. 2)Based on an alpha of 0.05, state your statistical decision in regard to the null hypothesis (step 6). Select either "reject" or "fail to reject".

1) 1.97 2) fail to reject

Assume the average height for American women is 64 inches with a standard deviation of 2 inches. A sorority on campus wonders if their members have a different height, on average, from the population of American women. The mean height of group, which includes 25 members, is 65 inches. 1) The z statistic for the sorority would be: (enter as a whole number rounded to the nearest 2 decimal places) 2) The approximate percentile for this sorority would be: (enter as a whole number, with no decimal, and no percent sign)

1) 2.5 2) 99

Time 1 and Time 2 scores were compared for 8 participants. The sample data showed a mean difference of 3.375, with a standard deviation for the difference values of 2.446. The researcher want to run a 2-tailed paired samples t test at an alpha of 0.05. 1)Calculate the t statistic: (Round your final answer to TWO decimal places.) 2)State the critical t: (list the positive value only, rounded to TWO decimal places)

1) 3.90 2)2.37

Some safety researchers were interested in the effects of a loud beeping noise on seat belt wearing in automobiles. Two groups of participants were randomly selected to test drive a new car. For one of the groups the car made a loud beeping noise as soon as a key was put in the ignition to reinforce seat belt wearing. For the other group, no noise was made when the key was put in the ignition. The researchers measured time taken to put on a seat belt in seconds. Does the loud beeping noise influence the amount of time people spend before putting on a seat belt? NOTE: Treat this as a two-tailed test, with a p level of 0.05. Calculate difference between the means as μ1 - μ2, where μ1 represents people who hear the beeping sound and μ2 represents people who do not hear the beeping sound. Answer the follownig questions: Based on this data, calculate the pooled variance: Beeping Noise 15 12 36 22 9 11 No Beeping Noise 16 27 19 34 24 1) Round your answer to the nearest TWO decimal places. 2) Based on the pooled variance, calculate the t statistic. Round to the nearest 2 decimal places. 3) Based on the hypothesis test in the last question, you would decide to:

1) 96.26 2) -0.79 3)Fail to reject null, because the t statistic is NOT in the critical region.

Researchers often use z tests to compare their samples to known population norms. The Graded Naming Test (GNT) asks respondents to name objects in a set of 30 black-and-white drawings. The test, often used to detect brain damage, starts with easy words like kangaroo and gets progressively more difficult, ending with words like sextant. The GNT population norm for adults in England is 20.4. Roberts (2003) wondered whether a sample of Canadian adults have different scores than adults in England. If they were different, the English norms would not be valid for use in Canada. The mean for 30 Canadian adults was 17.5. Assume the standard deviation of adults in England is 3.2. 1)If it is hypothesized that Canadians will have a lower mean, the researchers may choose to run a 1-tailed test (alpha = 0.05). For a one-tailed test, choose the appropriate null hypothesis. 2)(step 4) List the appropriate critical value for the 1-tailed test, using the correct sign (negative or positive). 3)(step 6) What conclusion do you draw from the hypothesis test, and why?

1) Canadian adults do not have lower average GNT scores than English adults. 2)-1.65 3)Reject the null, since the test-statistic value of z is in the critical region defined by the critical value.

Most tests that give IQ scores are designed to have a mean of 100 and a standard deviation of 15. IQ testing is one way in which people are categorized as having different levels of intellectual disability (the category formerly known as mental retardation). Prior to DSM-V, when the term mental retardation was used, four categories were distinguished. Two of those categories are shown below: -IQ of 20-35 (in combination with impaired life skills): severemental retardation -IQ of 50-70 (in combination with impaired life skills): mild mental retardation People with scores above 70 were not considered to have mental retardation. The IQ test was used first, and then, if a person's score fell into the range for mental retardation (70 or below) above, that person would be assessed for life skill impairments. A person has an IQ of 66. What is her percentile? (Enter a number without the percent sign, rounded to the nearest 2 decimal places)

1.16

Look at the following scatterplot and regression line. If a person were to increase his or her weight by 10 pounds, we expect the individual's waist girth to increase by ______ inches. (Answer using two decimal places.) y=9.9994+0.1332x

1.33

Suppose the null hypothesis states that there is no difference between the time 1 and time 2 quiz scores. What statistical decision follows from the information in the statistical software output? Paired Samples T-Test Time1 Time 2 t=0.838 df=24 p=0.410 Mean Difference=0.280 SE Difference=0.334

Fail to reject null, because the probability of this result being due to chance is > 0.05.

A researcher investigates if the extent to which people care about keeping their house clean and neat changes if they are given new things in that home. He follows eight families that were selected to receive home makeovers, assessing their cleanliness before the makeover and after. Given the following confidence interval [-1.26, 0.95], make a decision about the hypotheses.

Fail to reject the null hypothesis because zero falls in the confidence interval.

Based on the statistical software output, what is your decision in regard to the null hypothesis? IQ Score t=0.384 df=92.00 p=0.702 Note: For the Student t-test, the alternative hypothesis specifies that the mean is different from 100.

Fail to reject the null, because the p value is > 0.05.

For the following fictional conclusion, select whether the researcher seems to have rejected or failed to reject the null hypothesis (contingent, of course, on inferential statistics backing up the statement). Employee morale does not seem to be different, on average, whether employees work in cubicles or in enclosed offices.

Failed to reject the null

Correlation coefficients at or near -1.00 or 1.00 are relatively common.

False

If a test is reliable, then we know that it is valid.

False

Based on the equation: Yhat = 2.306 + 3.7X1 -2.9X2, how would you interpret the slope for X2?

For every -0.25 additional unit of X2 there is a 2.9 decrease in y-hat holding the X1 variable constant.

When creating a frequency table for the example below, select whether you should use individual data values or grouped data. Time to complete the London marathon for the more than 35,000 runners who participate

Grouped data

A consumer advocate is interested in evaluating the claim that a new granola cereal contains ''4 ounces of cashews in every bag.'' The advocate recognizes that amounts of cashews will vary slightly from bag to bag, but she suspects that the claim about the mean amount of cashews per bag is not true but rather an overestimation. What research hypothesis is she most interested in testing?

H1: μ < 4

The mean of the population is represented by the symbol ________ and the mean of the sample is represented by the symbol ________.

μ; M

South Korean researchers wondered how they could increase the number of people who turn off the light when leaving a room (Ahn, Kim, & Aggarwal, 2013). They compared 2 poster campaigns. In one, an image of a light bulb was anthropomorphized by giving it eyes, a nose, and a mouth, as well as adding the words, "I'm burning hot, turn me off when you leave!" In the second, there were no human features on the light bulb and the text simply said, "Our bulbs are burning hot, turn the lights off when you leave!" Participants were randomly assigned to view one of these posters and then were asked to rate a series of items about how likely they would be to behave in an environmentally friendly manner. The scale went from 1 (very unlikely) to 9 (very likely). After collecting data and running a 2-tailed independent samples t test, the researchers concluded "Reject the null hypothesis." With a 1 sentence response, interpret this statistical decision.

There is enough information and evidence to support a statistical difference in the rating of environmental friendliness between the group that viewed the poster with the anthropomorphized lightbulb and the one that was a basic lightbulb.

Twenty college students experience the effects of alcohol on reaction time. They perform very basic timed responses in a driving simulator both before and after consuming several alcoholic beverages. The researcher collects a reaction-time result for each of the 20 students before and after intoxication, for a total of 40 measures. What is the 2-tailed null hypothesis for this paired-samples study?

There is no difference in reaction time before and after consuming alcohol.

A light bulb manufacturer wants to ensure that the mean lifetime of a light bulb is 500 hours. If the testing program illustrates that the mean lifetime of a light bulb is only 125 hours, which is in the critical region, the null hypothesis is rejected. Should these light bulbs be sold? Please choose the correct answer from the following choices, and then select the submit answer button.

These lights should not be sold. Because the null hypothesis is rejected, the manufacturer now knows that these light bulbs did not meet the 500-hour lifetime criterion, indicating there is some type of manufacturing defect.

A new GRE prep class finds a sample from a recent session of their class has average scores that produce an effect size of d = -0.25 compared to the known GRE average. Interpret this effect size.

This effect size means that the sample mean was below the population mean (the original GRE average mean is larger than the new GRE mean) making the Cohen's d value negative. The negative effect size means that the effect decreases your mean. The average score was .25 standard deviations below the known mean. It would be a (negative) small effect.

Dr. Grooning conducts a study to test whether a new drug developed to treat general anxiety disorder works better than the usual treatment of cognitive behavioral therapy (CBT). The participants are randomly assigned to either the drug condition or the CBT condition. After 4 weeks of treatment, all of the participants complete the General Anxiety Test (GAT). The data reveal that the participants in the drug condition had lower GAT scores (i.e., less anxiety) than the participants in the CBT condition did. Dr. Grooning concludes that the new drug caused the more effective result. Which of these statements accurately describes Dr. Grooning's study?

This is an experimental research study, so a cause-effect relation can be inferred.

In a college class of 20 students, student age was measured and the results are provided in the following histogram. ( Starts high and decrease along x axis) Could the result pattern shown be due to a ceiling effect? Why or why not? (2 points)

This pattern could not happen from a ceiling effect however it could be due to a floor effect because it tails to the right.

Dr. Shipman designs a new test to assess depression in high school students. He determines that is has a coefficient alpha of 0.97. Based on this information, which statement is true?

This test has a high level of internal consistency.

Dr. Greeley designs a new test to assess depression in high school students and determines that it has a coefficient alpha of 0.27. Based on this information, which statement is true?

This test has a low level of internal consistency.

Researchers are interested in depressed individuals who are not responding to treatment. For their study, the researchers sample 18 patients from their own private clinics whose depression had not responded to treatment. Half received one intravenous dose of ketamine, a hypothesized quick fix for depression; half received one intravenous dose of placebo. The researchers hypothesized that individuals who received the ketamine would show a larger improvement in depression than individuals who received the placebo. The researchers found that more of the patients who received ketamine improved, as measured by the Hamilton Depression Rating Scale, usually in less than 2 hours, than patients on placebo. They concluded that ketamine significantly improves depression compared to a placebo. If the researchers were incorrect in their decision, what kind of error did they make? Explain.

Type I error; this would mean the researchers had concluded the drug was effective, but in reality, the new drug did not cause a difference in depression symptoms.

Garret thinks his car battery is becoming weak. He doesn't want to be stranded on the highway, so he tests his battery and it tests fine. But when Garret begins his trip on the highway, the battery dies 20 miles down the road. The test results must have been wrong! What type of error is this?

Type II

Why is it important to check for violations of assumptions when hypothesis testing?

We are making inferences about the population of interest that will be maximally valid if specific requirements are met.

histogram

We use a histogram to look at the distribution of a scale (interval or ratio) variable.

For which combination of variables might a researcher want to use the Mann-Whitney U test or the Kruskal-Wallis H test?

any ordinal variables

Dr. Zarayan wants to examine whether the average final score in her introductory psychology class, recorded as a percentage, differs depending on students' majors. To graph the data, she should use a(n) _____ graph.

bar

Researchers collect information on Major League Baseball players, including the position played, salary, and batting average. To look at the distribution of the variable "position," the researchers should make a:

bar graph.

Sun is reading an article about autism rates and how they are increasing in a majority of Western countries around the world. She notices that the authors used a _____ to depict the number of autism diagnoses in five different countries. This is the appropriate graph because the variables are _____.

bar graph; nominal and scale.

The population mean for certain aptitude test is known to be 35. To check the accuracy of this test, a random sample of individuals from the population is taken and then a 95% confidence interval of [32.15, 36.89] is calculated. If a 99% confidence interval were calculated based on the same data, it would _____ compared to the interval listed above.

be longer (include more values)

Suppose a study has a calculated t statistic of 2.87. If the value of M is increased by 15 but the rest of the values in the study stay the same, the researcher should anticipate that the t statistic will

become much larger due to the increase in the population mean.

Penny wonders whether athletes in some team sports have faster reaction times than athletes in other sports. She measures the reaction times of sample groups of basketball players, soccer players, football players, and baseball players. To analyze the resulting data, Penny will perform a(n):

between-groups ANOVA.

A clinical researcher was interested in determining whether his interventions for depression were effective in minimizing depression symptoms among his participants. To assess the effectiveness of his treatment program, he administered a depression inventory prior to his treatment and after his treatment. He hypothesized that depression scores would be lower at time two compared to time one. He then compared the mean differences between the two groups and found that his treatment was effective. Which statistical test was the researcher most likely to have used to test his hypothesis?

paired-samples t test

A negative correlation is an association between two variables in which:

participants with high scores on one variable tend to have low scores on the other variable as well.

After everyone finished the race, the organizers noted that while most runners finished in 6-8 minutes, a few participants actually walked and finished in 15 minutes. This distribution could be considered _____.

positively skewed

For a set of 50 numbers a researcher calculates the following measures of central tendency: mode = 5, median = 40, mean = 60. This distribution of this data would be considered:

positively skewed

Power is the probability of:

rejecting the null hypothesis when the research hypothesis is, in fact, correct.

A z test can be conducted only if there is one sample and if the mean and the _____ are known for the population. Please choose the correct answer from the following choices, and then select the submit answer button.

standard deviation

Based on the statistical software output, select the best representation of APA format for the results. Paired Samples T-Test Before After t=-3.576 df=15 p=0.003 Mean Difference=-1.125 SE Difference=0.315

t(15) = -3.576, p < 0.05

To determine the critical values for an independent-samples t test, you would use dftotal, which is:

the sum of N − 1 for each sample.

After conducting a paired-samples t test, the researcher should reject the null hypothesis if:

the test statistic is less than the lower cutoff or greater than the upper cutoff.

What is meant to be captured within a confidence interval?

the value of the unknown parameter

For which situation would it be appropriate to calculate r, the correlation coefficient?

time spent studying for a statistics exam and score on the exam

You are playing with a standard deck of 52 playing cards. Each time you draw one card from the deck and then you put the card back and reshuffle the deck before choosing another card. Drawing a card from the deck is a(n) ________.

trial

Leonard is studying the relationship between two scale variables. What will decide whether Leonard calculates the Pearson correlation coefficient or finds the regression equation?

whether Leonard is trying establish the strength of the association between the variables or is trying to use one variable to predict the other

Howard is observing the behavior of a scale variable in a single sample taken from a larger population where the variable's mean in the population is known. What will determine whether Howard uses a ztest or a single-sample t test?

whether the standard deviation of the variable in the population is also known

Researchers want to know if taking increasing amounts of ginkgo biloba will result in increased capacities of memory ability for different students. They administer this supplement to the students in doses of 250 milligrams, 500 milligrams, and 1000 milligrams. The amount of ginkgo will be plotted on the _____-axis.

x

The formula for z based on the mean of a sample (as opposed to a single data point) is:

z = (M - µM)/σM.

If the population's mean and standard deviation are known and there is only one sample, then a _____ can be conducted.

z test

If a researcher fails to reject the null hypothesis based on the results of a paired-samples t test, to draw the same conclusion based on the confidence interval:

zero would have to fall within the bounds of the confidence interval.

What symbol should always be used in the null and research hypotheses when testing the mean?

μ