Stats Practice Final - DuVall
Assume the following for a paired-sampled t test: N = 9, Mdifference = 13.19, s= 22.3. What is the t statistic?
1.77
A researcher collects 25 data points that yield a mean of 8.16 and a standard deviation (based on N-1) of 2.24. If the researcher is comparing the sample to a population mean of 9.2 using a single-sample t test, what would be the effect size?
-0.46
Which of these values indicates the strongest relationship between two variables?
0.48
Which formula for calculating the lower bound of a confidence interval is correct?
-t(sdifference) + (Mx - My)sample
Assume the average height for American women is 64 inches with a standard deviation of 2 inches. What percent of groups size 25 would have mean heights of less than 62 inches? (round z score of two decimal places)
0
Σ(X-M) is always equal to:
0
A coefficient alpha of ____ is considered a minimally acceptable level of reliability for measures that will be used to make decisions about individuals based on their scores on the measure.
0.90
If the standard deviation for a population, as estimated from a sample, is s = 3.8, then the standard error for a sample size of N = 16 is sM =:
0.95
(Figure: Frequency Polygon) Based on the frequency distribution, how many participants scores a 6?
1
(Table: Anxiety) The modal anxiety rating (or mode) in the data set is:
1.00
A perfect linear relationship will yield a Pearson correlation value of:
1.00 or -1.00
In the equation Y = 130 + 5(X1) + 3(X2), what is the y intercept?
130
(Table: Depression) What percent of participants rated their depression as 1?
14.29
To calculate effect size for an independent-samples t test, use:
Cohen's d.
One rejects the null hypothesis when the test statistic falls in which area of the distribution?
critical region
When multiple researchers recruit participants from various locations to replicate findings it is called
crowd-sourcing science
Jenny hypothesized that older adults would score higher on emotional intelligence measures when compared to younger adults in her study. If Jenny commits a false-negative error, she has committed a:
Type II error
As the correlation coefficient becomes stranger, the proportionate reduction in erroe:
becomes larger
Assume for a given study that the null hypothesis asserts that the expected value of a phenomenon is 100. A research study results in a 95 percent confidence interval reported as [98.76, 105.24]. What decision should be made based on this confidence interval?
fail to reject the null hypothesis
What would be the decision for the following paired-samples t test: t(24) = 1.11, p > 0.05?
fail to reject the null hypothesis
The most frequently occurring score in a distribution is the
mode
The standardized regression coefficient expresses the:
predicted change in the dependent variable in terms of standard deviations, for an increase of 1 standard deviation in the independent variable.
The technical term for a distribution that is lopsided, off-center, or otherwise nonsymmetrical is_____.
skewed
In the formula = a + b(X), b is the:
slope
In the formula Y= a+b(X), b is the:
slope
When performing a single-sample t test, an effect size of 0.20 would be interpreted as a ____ effect.
small
Recent research published by Frumin and colleagues (2011) in the journal Science addresses the question of whether females' tears have an effect on males. Imagine that exposure to tears lowered self-rated sexual arousal by 1.27 points, with a margin of error of 0.32 points. The point estimate is _____, while the interval estimate is _____.
1.27; [0.95, 1.59]
(Table: Anxiety) The variance in this data set is:
1.43
If the standard deviation for a population, as estimated from a sample, is s = 6.47, then the standard error for a sample size of N = 20 is sM =:
1.45
The most widely used measure of reliability is:
coefficient alpha, the average of all possible split-half correlations
Assume the following for a paired-sample t test: N = 19, Mdifference = 13.19, s= 22.3. What is the effect size using Cohen's d?
0.59
A coefficient alpha of _____ is considered a minimally acceptable level of reliability for measures that will be used to make decisions about individuals based on their scores on the measure.
0.90
If the standard deviation for a population, as estimated from a sample, is s = 6.47, then the standard error for a sample size of N = 20 is sM=:
1.45
Assume the following for a paired-samples t test: N = 9, Mdifference = 13.19, s = 22.3. What is the t statistic?
1.77
Six students from a psychology class reported the number of hours of television they watch per week. Here are their data: 18, 12, 15, 14, 13, 16. What is the standard deviation of the number of hours of television watched per week for this sample of six students
1.97
Six students from a psychology class reported the number of hours of television they watch per week. Here are their data: 18, 12, 15, 14, 13, 16. What is the standard deviation of the number of hours of television watched per week for this sample of six students?
1.97
A researcher analyzed the results of her data and calculated the variance of scores at 113.00. What is the standard devuation?
10.63
If the percentage of scores falling between the mean and a z score of 0.30 is 11.79, then what is the percentage of scores falling between the mean and a z score of -0.30?
11.79
(Figure: years of education) What is the range of this distribution?
12
This histogram represents the distribution of the number of years of education completed by twins who attended the 16th Annual Twins Day Festival in Twinsburg, Ohio, in August of 1991.
12
This histogram represents the distribution of the number of years of education completed by twins who attended the 16th Annual Twins Day Festival in Twinsburg, Ohio, in August of 1991.Figure: Years of Education
12
In a standard deck of playing cards, there is a total of 52 cards, 12 of which are face cards, such as queens, kings, and jacks. What is the formula for the expected relative-frequency probability of drawing a single face card from the deck of cards?
12/52
(Table: Happiness) How many participants did not rate their happiness as either 4 or 5
13
Six students from a psychology class reported the number of hours of television they watched per week. Here are their data: 18, 12, 15, 14, 13, 16. What is the median number of hours of television watched per week for this sample of six students?
14.5
The results of an independent-sample t test were t(19)=4.02, p< 0.05 in this example, the degree of freedom are:
19
This table represents the fictional scores of a set of participants who rated their anxiety levels for the past two weeks on a scale of 1 to 4, 1 indicating No Anxiety and 4 indicating Anxiety (mean)
2.11
Which set of scores has the least amount of variability?
22, 26, 21, 23
In one statistics course, students reported studying an average of 9.92 hours a week, with a standard deviation of 4.54. Treating this class as the population, what percent of study more than 13 hours a week? (Round z score to two decimal places)
24.83
Six students from a psychology class reported the number of hours of television they watch per week. Here are their data: 18, 12, 15, 14, 13, 16. The variance of the number of hours of television watched per week for this sample of six students is:
3.89
(Table: Optimism) The variance in this data set is:
3.96
(Table: Age) The modal age (or mode) in this data set is:
33.00
(Table: Age) The median age in this data set if
39.00
What is the percentage of observations that fall between z scores of -1.02 and 0.61?
57.52
(Table: Optimism) the range in this data set is:
6
Brent tosses a quarter four times and three times it comes up heads. The percentage of heads is:
75%
(Table: Happiness) How many participants rated their happiness as 6 or higher?
8
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
When conducting a hypothesis test for the Pearson correlation coefficient, degree of freedom is calculated by:
N-2
When conducting a hypothesis test for the Pearson correlation coefficient, degrees of freedom is calculated by:
N-2
A researcher discovers that the length of time spent following a Mediterranean diet is negatively correlated with the risk of developing cancer. Which statement logically follows from this information?
People who followed a Mediterranean diet for longer periods were less likely to have cancer
The symbol for the population standard deviation is:
S
What is the basic formula for the variance?
SD = Sum(X-M)2/N
Claire knows the z score for her research hypothesis is -2.05, and her critical values are -1.96 and 1.96 for a p value of 0.05. What should she conclude about her hypothesis given these statistics?
She should reject the null hypothesis and report the direction of the effect because the score is in a critical region (below -1.96).
A psychologist is interested in whether working memory is influences by sleep loss. The psychologist administers a measure of working memory to a group of subjects at 8 a.m. on Day 1 of the study and then again at 8 a.m. on Day 2 of the study, after keeping the subjects awake the entire night. Does sleep loss affect working memory? What statistical analysis should be performed to answer this question?
paired-sample t test
A study by Bettmann (2007) published in the Journal of the American Psychoanalytic Association assessed whether the attachment relationship between adolescents and their parents change as a result of a residential wilderness treatment experience for the adolescents. Participants complete the Adolescent Attachment Questionnaire at the start and at the end of the wilderness program. Which statistical test should be used to determine whether the wilderness treatment affected attachment relationship?
paired-sample t test
A study by Bettmann (2007) published in the Journal of the American Psychoanalytic Association assessed whether the attachment relationship between adolescents and their parents change as a result of a residential wilderness treatment experience for the adolescents. Participants completed the Adolescents Attachment Questionnaire at the start and at the end of the wilderness program. Which statistical test should be used to determine whether the wilderness treatment affected attachment relationships?
paired-sample t test
what would be the decision for a two-tailed paired-sample t test where the confidence interval was determined to be [1.34, 6.45]
reject the null hypothesis
A duplication of scientific results in a different context or with a different sample is:
replication
Based on research, Peter knows that the correlation coefficient between the level of management and concern regarding the environment is -0.85. If the critical value for r is 0.250, what should he conclude?
The level of management is significantly related to concern regarding the environment
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 population in this study?
b. all adolescents, both overweight and not overweight, who play DDR
The formula is used to calculate the:
b. estimated standard deviation of the distribution of differences between means.
When conducting a paired-samples t test, one can assess the practical importance of the obtained results by calculating:
an effect size measure
Meredith is a nurse in the obstetrics ward of the local hospital. She tells her friend that at her hospital more babies are born when there is a full moon. The hospital's records show no such relationship, however. Meredith's belief is an example of:
an illusory correlation
Why is it necessary to use the pooled variance when conducting an independent-samples t test
b. We are working with two samples, and an estimate of spread based on two samples is likely to be more accurate than an estimate of spread based on a single sample.
A simple way to calculate the proportionate reduction in error is by:
b. squaring the correlation coefficient.
A marketing specialist for a major department store wants to know how much time people tend to spend in the store so that the audio advertisement will replay on a timed loop, allowing every customer a change to hear each unique message. What information is this marketing specialist seeking?
centeral tendency
In a(n) ______, each participant is assigned to only one group in order to compare differences amongst the two groups.
independent-samples t test
If you wanted to know whether judges in your state are typically male or female, what measure of central tendency would you use to describe the typical judge?
mode
As the sample size becomes larger, the t distributions look ____ the z distribution
more like
A researcher wants to predict the first-semester grade point average of first year college students with as much accuracy as possible. She would like to use both high school grade point average and SAT score as predictor variables. Which technique would be most appropriate to make this prediction?
multiple regression
As the sample size becomes larger, the t distribution becomes:
narrower
As the sample size becomes larger, the t distributions become:
narrower
What king of correlation can be seem in the sentence "the older a man gets, the less hair that he has?"
negative
(Table: Grouped Frequency Table)What seems to be the shape of the distribution represented in this grouped frequency table?
negatively skewed
Twenty people participate in a weight-loss program for 2 months. Their weights after the 2 months are compared to their starting weights. What kind of mean difference might be expected if the null hypothesis is true for a paired-samples t test?
no change in weight or weight gain, indicating that the program does not work
When conducting a hypothesis test for the Pearson correlation coefficient, the null hypothesis states that there is _____ between the two variables
no correlation
The scatterplot, created from 1995 U.S. News & World Report data on approximately 1,300 U.S. colleges and universities, depicts the relation between the student-faculty ratio at the school and the number of admissions applications the school received.Figure: Student-Faculty Ratio
no relation
a person's political affiliation is a(n)_____variable.
nominal
A clinical researcher was interested in determining whether her interventions were effective in minimizing depression symptoms among participants. To assess the effectiveness of the treatment program, she administered a depression inventory prior to treatment and after treatment. She hypothesized that depression scores would be lower at time two compared to time one. She then compared the mean differences between the two groups and found that the treatment was effective. The independent variable in this study is:
time
To determine the critical values or cutoffs for an independent - sample t test, use:
total degrees of freedom
Researchers were interested in whether relaxation training decreased the number of headaches a person experiences. They randomly assigned 20 participants to a control group (no relaxation training) or a relaxation training group and noted the change in number of headaches each group reported from the week before training to the week after training. The independent variable in this study is:
training type
Data from the World Health Organization in 2013 were used to predict the life expectancy of men in a country from the life expectancy of women in that country. The resulting regression equation was = 3.73 + 0.88( X). This regression equation implies that:
when a woman's life expectancy increases by 1 year, a man's life expectancy increases by 0.88 of a year.
In a re-analysis of published studies, Twenge and Im (2007) found that for the time period of 1958 to 2001, the need for social approval of people in the United States was positively correlated with changes in the Dow Jones industrial Average during that same period (the correlation coefficient was 0.10). This means that:
when the need for social approval was high, the Dow Jones industrial Average was also high
In a sample of data that has several extremely high scores, creating positive skew, the mean:
will be greater than the median
What is the relationship between correlation and causation?
correlation is necessary for causation
To calculate a confidence interval for an independent-sample t test, use the:
difference between means
To calculate a confidence interval for an independent-samples t test, use the:
difference between means
The comparison distribution for an independent-sample t test is a distribution of:
differences between means
the comparison distribution for an independent-samples t test is a distribution of:
differences between means
When calculating a z test, one compares data from the sample to a:
distribution determined by the null hypothesis
A _____ is composed of means based on samples rather than raw scores.
distribution of means
What is the correct formula for calculating a probability?
divide number of successes by number of trials
The first step in calculating a confidence interval for an independent-samples t test is to:
draw a normal curve
in addition to reporting the results of statistical testing, it also recommended that researchers report
effect size and confidence intervals
In addition to reporting the results of statistical hypothesis testing, it is also recommended that researchers report:
effect size and confidence intervals.
Why are effect sizes rather than test statistics used when comparing study results?
effect sizes, unlike test statistics, are not affected by sample size and thus, ensure a fair comparison
For a simple linear regression, the standardized regression coefficient is:
equal to the Pearson correlation coefficient
The regression line is the line that minimizes:
error in predicting scores on the dependent variable
The denominator (bottom portion) of the ratio for calculating the paired-samples t statistic is the:
estimated standard error of the distribution of mean difference scores
Random assignment refers to a situation in which:
every participant in the study has an equal chance of being assigned to any condition or level of the independent variable.
hypothesis testing tells
what results are significant, but no details regarding the meaning of the significant results.
(Table: Optimism) The range in this data set is:
6.00
In an independent-samples t test, how is the null hypothesis symbolized?
H0: μ1 = μ2
The formula for the null hypothesis for a paired-sample t test is:
H0: μ1 = μ2
In an independent-samples t test, how is the research hypothesis symbolized
H1: 1 does not equal 2
What is the formula for the single-sample t statistic?
(M - μM)/sM
What is the correlation between a person's weight as measured in grams and a person's weight as measured in pounds?
+1.00
A correlation is computed using data from 28 people. What is the critical cutoff for a two-tailed hypothesis test with a p level of 0.05?
-0.374 and 0.374
A researcher collects 25 data points that yield a mean of 8.16 and a standard deviation (based on N - 1) of 2.24. If the researcher is comparing the sample to a population mean of 9.2 using a single-sample t test, what would be the effect size?
-0.46
Adam scored 45 on his final exam. His class's average score was 50, with a standard deviation of 10. What is Adam's z score?
-0.5
Which of these values of the correlation coefficient indicates the strongest relationship between two variables?
-0.72
Which of these represents a perfect correlation?
-1 or 1
Which of these correlation coefficients allows a perfect prediction of scores on one variable from the knowledge of score on the other variable?
-1.00
The numerical value for a coefficient ranges between _____ an ____
-1.00; 1.00
Gibson (1986) asked a sample of college students to complete a self-esteem scale on which the midpoint of the scale was the score 108. He found that the average self-esteem score for this sample was 135.2, well above the actual midpoint of the scale. Given that the standard deviation of self-esteem scores was 28.15, what would be the z score for a person whose self-esteem score was 104.28
-1.10
The critical value(s) associated with a p level of 0.05 for a one-tailed hypothesis test using the z statistic is(are):
-1.65 or 1.65
The critical value(s) associated with a p level of 0.05 for a two-tailed hypothesis test using the z statistic is (are):
-1.96 and 1.96
What percent of scores fall beyond 2 standard deviations away from the mean?
4
What percentage of scores fall beyond 2 standard deviations away from the mean?
4
(Table: Coefficients) What is the y intercept for this problem?
4.974
Here is a set of data: 31, 54, 26, 42, 39, 45, 38, 42. What is the median?
40.5
This table represents the fictional scores of a set of participants who rated their happiness on a scale from 1 to 7, with 1 indicating very unhappy and 7 indicating very happy.The most frequently occurring score in this data set is:
5
If the variance of some data is 26.84, what is the standard deviation?
5.18
(Table: Optimism) The mean in this data set is:
5.43
in one statistics course, students reported studying an average of 9.92 hours a week, with a standard deviation of 4.54. The professor tells Mackenzie she scored at the 46th percentile. How many hours does she study per week? (Round z score to two decimal places)
9.47 hours
A p level of 0.05 corresponds to a confidence interval of _____ percent
95
In a normal standard curve, approximately _____ percent of scores fall within 2 standard deviations from the mean
96
A p level of 0.01 corresponds to a confidence interval of _____ percent
99
Here is a set of score: 18, 99, 14, 16, 31, 43, 12, 13, 51, 12. What score is considered to be an outlier?
99
A researcher is interested in predicting the efficiency levels of employees from the number of absences taken ( X 1) and the number of hours working each day ( X 2).The slope of X 1 is 8, the slope of X 2 is -3, and the y intercept is 62.2.Which is the regression equation for these data?
=62.2+ 8(X1)-3(x2)
(Study Description: Tail Wagging) Which statement is the null hypothesis for this study?
A dog's tail wagging will be the same in response to positive stimuli as the negative stimuli
The behavioral sciences typically use alpha of 0.05. How do they represent this value and what does it mean?
A p value, which means scores in the most extreme 2.5 percent on either end of the distribution, will be evidence to reject the null hypothesis.
When conducting a paired-sample t test, one can assess the practical importance of the obtained results by calculating:
an effect size measure
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. Which of these statements represents the proper way to summarize his results regarding the null and research hypotheses?
Fail to reject the null hypothesis and conclude that, based on this study, he did not observe an effect for colorful socks.
A researcher investigates whether 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 confidence interval [-1.26, 0.95], what decision about the hypothesis should be made?
Fail to reject the null hypothesis because 0 falls in the confidence interval
A man and woman who are both tall (he is 6 feet tall and she is 5 feet, 10 inches tall) have four children. Which child represents regression to the mean for height?
Laura, who it 5 feet, 5 inches
Which of the following is an example of multiple regressions?
The effect of the price and the sweetness of a pastry affecting a taster's rating
A community researcher wanted to explore the connection between the number of bathrooms in a house and the sale price of the house. He studied 1750 home sales in an economically diverse, medium-sized city, and he found that the average sale price went up by $63,000 for each full bath. Which statement involves a logical inferential statistic based on this research
On average, adding a bathroom to your house can increase the sale price
What is the formula for the pearson correlation coefficient?
Sum [ (X-Mx) (Y-My)]/square root (SSx)(SSy)
"The incidence of depression among college students is negatively correlated with the number of sunny days each year in the locale where they attend college" This statement means that:
The chances of a college student being depressed tend to increase with fewer sunny days
What information do the slopes in a multiple equation provide about the correlation coefficient?
The sign of the slope (positive of negative) tells us the direction of the correlation
A study found statistically significant results for a hypothesis tested with an independent-samples t test. The author of the study reported her effect size for the test as 0.53. What is true of the two sample means?
The two sample means are 0.53 standard deviations apart
A distribution of score has a mean of 20.2 with a standard deviation of 0.89. Compare a score of 21.26 with a z score of 1.2. Which statement is correct?
The z score of 1.2 is greater, resulting in a raw score of 21.27
Why is it necessary to use the pooled variance when conducting an independent-samples t test?
We are working with two samples, and an estimate of spread based on two samples is likely to be more accurate than an estimate of spread based on a single sample.
Hypothesis testing tells:
What results are significant but no details regarding the meaning of the significant results
Which statement regarding the denominator of the equation for the z score and that of the z statistic is true?
When computing a z score, we divide by the population standard deviation, but when computing a z statistic, we divide by the standard error of the sampling distribution.
Marco insists that women are poorer drivers than men. To back up his claim he describes two incidents: one in which his girlfriend sideswiped a car and a second in which his mother failed to react in time to avoid hitting a squirrel on the highway. Marco's attention to this positive evidence for his belief reflects:
a confirmation bias
When conducting a hypothesis test for the Pearson correlation coefficient, the research hypothesis states that there is _____ between the two variables
a correlation
The consideration of future consequences scale is intended to measure the extent to which an individual considers the future when making immediate choices. If the scale is a reliable measure, we would expect that:
a person's score on the scale would be relatively stable from day to day
When attempting to find a percentage associated with a z score, the second step involves looking up:
a z score on the z table
The standard error of the estimate is the standard deviation of the ____ data points around the regression line
actual
A medical researcher interested in asthma symptoms wanted to know how symptoms were affected in dry versus humid conditions. The researchers recruited 18 asthma patients to spend four weeks under two conditions: sleeping with a dehumidifier for two weeks to create a "dry" environment and sleeping with a humidifier for the remaining two weeks to create a "humid" environment. Patients were asked to rate their symptoms at regular intervals using a scale from "0 - no symptoms" to "20 - maximum asthma symptoms." The change in asthma symptoms from dry to humid conditions was 5.82, showing a reduction of symptoms in humid conditions. What is MOST likely the population of interest for this researcher?
all asthma sufferers
According to the null hypothesis, the mean difference for the comparison distribution in a paired-samples t test is:
almost always 0
The proportionate reduction in error is a measure of the:
amount of variance in the dependent variable explained by the independent variable
Why does one divide by N -1 rather than by N when estimating a population standard deviation from the sample standard deviation?
because the sample standard deviation is likely to be imprecise estimate, we allow the error of the estimate (the standard deviation) to be larger by dividing the sum of squares by a smaller number
As the correlation coefficient becomes stronger, the proportionate reduction in error:
becomes larger
The results of a study find a positive correlation between gum chewing and life expectancy. Which statement would be a statistically appropriate response to the results of the study?
becoming curious about what third variable might cause an increase in both gum chewing and increases in life expectancy
In a study designed to predict blood cholesterol levels from the amount of daily saturated fat in grams ( X 1) and the number of hours of daily exercise ( X 2), the slope of X 1 is 5, the slope of X 2 is -4, and the y intercept is 130. Which formula is the regression equation for these data?
c. = 130 + 5(X1) - 4(X2)
(Figure: Standard Error Comparisons) For which prediction is the standard error of the estimate greater?
composite SAT scores from the state's expenditure per student
A researcher is interested in comparing reaction time differences between men and women. He obtains a sample of 45 students from a psychology student research database. Participants take part in the study, the data are later analyzed, and the researcher concludes that women have faster reaction times than men. What type of sampling strategy was used in this study?
convenience
The fourth step in calculating a confidence interval for an independent-samples t test is to:
convert the t statistic to raw difference between means
When conducting a hypothesis test for the Pearson correlation coefficient, the research hypothesis states that there is______ between the two variables.
correlation
As r2 increases, the standard error of the estimate:
decreases
a behavioral neuroscientist is testing the effects of adrenaline on memory using a group of 12 rats. The researcher is unsure about how much adrenaline might produce an effect on memory. One group will be injected with placebo saline (0 micrograms of adrenaline). The other group will be injected with a dose of adrenaline. When deciding between a 2-microgram dose or an 8-microgram dose(both of which are safe), the researcher opts to use the 8-microgram does. The researcher has:
exaggerated the difference between the levels of the independent variable, thereby increasing statistical power
The likelihood of an expected outcome if an experiment if an experiment is repeated many, many times is the:
expected relative-frequency probability
A paired-sample test is reported as t(18) = 1.73. What decision about this test should be made, assuming a two-tailed hypothesis test with a p level of 0.05?
fail to reject the null hypothesis
Following a meta-analysis, the researcher might decide to perform a(n) _____ to determine the number of null results that would have to exist to overturn any statistically significant effect found in the meta-analysis.
file drawer analysis
A _____ is a visual depiction of data that shows how often each value occurred.
frequency polygon
Dr. Jameson wanted to know if IQ scores differed between male and female participants in his study. He gave 28 participants an IQ test and then compared IQ scores for gender differences. He hypothesized that there would be a statistically significant gender difference in IQ scores. Contrary to Dr. Jameson's hypothesis, there were no differences in IQ scores between men and women in his study. What is the independent variable in this study?
gender
A researcher has conducted a study on logical reasoning using a sample of college freshman, he is concerned, however that the results of the study not accurately depict the logical reasoning of college seniors. The researcher's concern can be described as a concern about the ____ of the study results.
generalizability
A researcher has conducted a study on logical reasoning using a sample of college freshmen; he is concerned, however that the results of the study may not accurately depict the logical reasoning of college seniors. The researcher's concern can be described as a concern about the _____ of the study results.
generalizability
The class average on Professor Bhatt's midterm for statistics was a 68. Because this score was unexpectedly low, she has decided to award every student an additional 5 paints. Adding these 5 points will ____ the distribution of scores.
have no effect on the shape of
As sample size ____, the spread of distribution of means decreases
increases
As sample size ______, the spread of distribution of means decreases.
increases
Increasing sample size:
increases the likelihood that we will reject the null hypothesis
In a(n)_____, each participant is assigned to only one group in order to compare differences amongst the two groups
independent-sample t test
What would be the decision for a two-tailed paired-sample t test where the t statistic is -4.67, with cutoffs of ± 2.776
reject the null hypothesis
If a study fails to replicate:
it can help us better understand that context under which findings might exist
A major reason replication of scientific findings has rarely been attempted is because:
journals tend to publish only new research
A study found statistically significant results for a hypothesis tested with an independent-sample t test. The author of the study reported her effect size for the test as 0.87. According to Cohen's conversions, this effect size is considered:
large
As standard error of estimate becomes larger, predictions become:
less accurate
As the standard error of estimate becomes larger, predictions become:
less accurate
A researcher was interested in the effects of gender on attitudes toward women in leadership positions. The researcher surveyed a group of individuals, 12 of whom were men and 12 of whom were women. In this example, men is a(n) _____ variable.
level of the independent
If a negative relation exists between two variables, then high scores on one variable will be associated with _____ scores on the other variable.
low
If the assumptions of parametric testing are not met, researchers must:
make a decision to continue with parametric or nonparametric tests
In a paired-samples t test, the comparison distribution is a distribution of:
mean difference scores
repeated sampling of ___ approximates a normal curve, even when the underlying population is skewed
means
Mehl et al. (2007) published a study in the journal Science reporting the results of an extensive study of 396 mean and women in which the number of words uttered per day by each sex were compared. They found that on average women uttered 16,215 words a day and men uttered 15,669 words a day. The effect size calculated on the basis of their findings is Cohen's d = 0.07. This effect size indicates that the:
means of the men and women are not even one-tenth of 1 standard deviation apart
Mehl et al. (2007) published a study in the journal Science reporting the results of an extensive study of 396 men and women in which the number of words uttered per day by each sex were compared. They found that on average women uttered 16,215 words a day and men uttered 15,669 words a day. The effect size calculated on the basis of their findings is Cohen's d = 0.07. This effect size indicated that the:
means of the men and women are not even one-tenth of 1 standard deviation apart
If you knew nothing about your data except that it is a scale variable, which measure of central tendency would be the "safest bet"?
median
The _____ are both relatively insensitive to outliers.
median and mode
When performing a single-sample t test, an effect size of 0.50 would be interpreted as a _____ effect.
medium
Inferential statistical analyses that are NOT based on a set of assumptions about the underlying population are:
nonparametric tests
A statement that postulates that there is no difference between population is a:
null hypothesis
H0: μ 1 = μ 2 is used to represent the:
null hypothesis
A regression equation is likely to be a better predictor when using more than:
one independent variable
The crowd-sourcing movement in research is
open science
An independent variable that makes a unique contribution to the prediction of a dependent variable is a(n)_____variable
orthogonal
If two variables, independently, can help predict the outcome of a third variable, they are:
orthogonal
One rejects the null hypothesis only when the:
p value associated with the test statistic is smaller than the p level chosen
What is the null hypothesis when testing for significance using the Pearson correlation coefficient?
p=0
What is the research hypothesis when testing for significance using the Pearson correlation coefficient?
p=0
In a(n)______, a within-groups design with two groups is used to compare the distribution of mean difference score
paired - sample t test
A clinical researcher was interested in determining whether her interventions for depression were effective in minimizing depression symptoms among her participants. To assess the effectiveness of her treatment program, she administered a depression inventory prior to treatment and after treatment. She hypothesized that depression scores would be lower at time two compared to time one. She then compared the mean differences between the two groups and found that her treatment was effective. Which statistical test was the researcher MOST likely to have used to test her hypothesis
paired samples t test
In a physical geography course, the average score on the first exam across all sections of the course was 77.63 percent. Because all students were included in the calculation, the mean is assumed to be based on population data. The test average may be considered to be a:
parameter
A positive correlation between head size and foot size indicates that
people with large feet tend to have large heads
The percentile rank is the:
percentage of scores falling at or below a particular raw score
in the equation for a regression line, the intercept is the:
predicted value for Y when X is equal to 0
Which statistic quantifies the improvement in the ability to predict a person's score when using the regression line rather than the mean?
proportionate reduction in error
Regression cannot prove causation, but it can:
provide specific quantitative predictions that help to explain relations among variables.
The Pearson correlation coefficient is symbolized by:
r
Proportionate reduction in error can be symbolized by:
r^2
There are three steps involved in creating the comparison distribution for the independent-sample t test, and those steps are represented many times. Which of these is the sequence described in the text?
randomly select scores and calculate their mean as the group 1 mean, randomly select another group of scores and calculate their mean as the group 2 mean, and subtract the second mean from the first test.
The_____ is the difference between the lowest and highest score in the distribution.
range
To determine a person's percentile, first convert the person's _____ score to a z score.
raw
A ______ is a data point that has not yet been transformed or analyzed
raw score
When attempting to find a percentage associated with a z score, the first step involves a _____ to _____ transformation.
raw score; z score
Which statistical tool allows one to predict a dependent score based on information about an independent variable?
regression
Jenny hypothesized that older adults would score higher on emotional intelligence measures when compared to younger adults in her study if the results are in support of Jenny's hypothesis, she would:
reject the null hypothesis
Why are true random samples rarely used?
researchers rarely have access to the entire population
The standard deviation of a distribution of scores in a sample is known as _____, while the standard deviation of a distribution of means is referred to as _____.
s; sM
A_______is a graphical representation of the relationship between two variables.
scatterplot
Before calculating the correlation coefficient, it is advisable to create a _____as a way of displaying the association between the two variables
scatterplot
What is the correct formula for calculating the standard deviation of a sample when one is NOT trying to estimate the population standard deviation?
square root ( (sum (X - M)2)/ N)
What is the correct formula for using the sample standard deviation to estimate the population standard deviation?
square root ( sum(X -M)2/(N-1))
Variance is the average of deviations around the mean expressed in ____ units.
squared
The process of standardization involves the conversion of raw scores to _____ scores.
standard
The standardized regression coefficient expresses a predicted change in the dependent variable in terms of:
standard deviation units
If one rejects the null hypothesis, the result is said to be:
statistically significant
Numbers that describe samples are called
statistics
The numerator (top half) of the Pearson correlation coefficient formula includes the:
sum of the product of the deviations for each variable
When the population mean is known and the population standard deviation is not known, which statistic is used to compare a sample to the population?
t
The correct formula for the upper bound of a confidence interval for a single-sample t test is:
t(Sm) + Msample
Which statisticians describe pooling the variances, they mean:
taking the average of the two variances, accounting for sample size
Because of _____, skewed distributions approximate normal curves when means are based on larger samples.
the central limit theorem
Because of the principle of _______, when sample sizes are at least 30, that distribution will most likely resemble a normal distribution.
the central limit theorem
Which statement is NOT an assumption of the z test?
the distribution of the sample is normal
The statement "On average, older adults have the same response time as younger adults" is an example of:
the null hypothesis
A negative correlation between a hockey player's age and the number of minuets he spends in the penalty box indicates that:
the older a player is, the less time he spends in the penalty box
Statistical power is:
the percent of the comparison distribution that falls beyond the critical cutoff
The single-sample t test compares a sample mean to a population mean when:
the population standard deviation in unknown
If all the points on a scatterplot fall on a single line, then
the relation between the variable is perfect
If all the points on a scatterplot fall on a single line, then:
the relation between the variables is perfect
two students recently took algebra class tests. the students are at different schools but wanted to compare their performance. The first student scored 80 on the test. Her class average was 90 with a standard deviation of 10. The second student scored 70. Her class average was 50 with a standard deviation of 10. Which student did better?
the second student because she performed better relative to her class
All of the recent children born into Jessica's family have been males, so there is a lot of pressure for her and her husband Matt to have the first granddaughter. In fact, everyone is sure that their first child will be a girl, because the family is due to have one! Unfortunately for their families, this logic is false because.
the sex of their child is independent of that of any previous children born
What information do the slopes in a multiple regression equation provide about the correlation coefficient?
the sign of the slope (positive or negative) tell us the direction of the correlation
The concept of variability is best described as:
the spread there is in the distribution of data
A study statistically significant results for a hypothesis tested with an independent-sample t test. The author of the study reported her effect size for the test as 0.53. What is true of the two sample means?
the two sample means are 0.53 standard deviations apart
A study found statistically significant results for a hypothesis tested with an independent-samples t test. The author of the study reported her effect size for the test as 1.24. What is true of the two sample means?
the two sample means are 1.24 standard deviations apart
The standard error of the estimates indicates
the typical distance between the regression line and each of the observed data points
The standard error of the estimate indicates:
the typical distance between the regression line and each of the observed data points.
The concept of central tendency is best described as:
the value around which the data seem to gather
A paired-samples t test is reported as t(15) = 0.918, p > 0.05, d = 0.17. What is the effect size for this statistical test?
this is a small effect
Researchers were interested in whether relaxation training decreases the number of headaches a person experiences. They randomly assigned 20 participants to a control group (no relaxation training) or a relaxation training group and noted the change in number of headaches each group reported from the week before training to the week after training. The independent variable in this study is:
training type
The statement, "it is hypothesized that participants in a stress condition will perform in a significantly different manner than participants in a control group on a series of memory tasks' best illustrates a:
two-tailed test
The text claims that journals tend to prefer "exciting" findings over "boring" ones. Because of the drive to publish new findings that go against the status quo, the literature is assumed to contain _____ errors.
type I
When a test measures what is is intended to measure, the test is said to be
vaild
If a test actually measures what it is intended to measure, then that test is :
valid
Errors in prediction lead to ____.
variability
If a dependent variable is nominal, the assumption that the ____ should not be made.
variable is assessed using a scale measure
Squared standard deviation is equivalent to the:
variance
Under what condition is it permissible to proceed with a hypothesis test even though the assumption that participants are randomly selected is violated?
we are cautious about generalizing the results
When considering the results from an opinion poll, where several verbal expressions are each rated for their level of annoyance, what is particularly useful about margins of error is that:
we can figure out more than one interval estimate for the same poll to see is they overlap.
external validity is ____by the use of volunteer samples
weakened
A New York Times article publishes on April 24, 2007, reported the research of Dr. Giorgio Vallortigara, a neuroscientist at the University of Trieste, Italy. In this study Dr. Vallortigara recruited 30 dogs that were family pets. While filming a dog's tall from above, he allowed the dog to view (through a slot in its cage) its owner, an unfamiliar human, a cat and an unfamiliar dominant dog. The study found that the dogs tails wagged to the right for the owner and to the left for the unfamiliar dominant dog. What type of research design did Dr. Vallortigara employ?
within-groups
The z distribution is equivalent to a distribution of ____ scores.
z
The z distribution is equivalent to a distribution of _____ scores
z
The formula for calculating a z score is
z = (X - μ)/s
The average salary for all 27 Arizona Diamondbacks in the 2012 baseball season was $2,653,029, with a standard deviation of $2,587,139. The population, all National League baseball players in 2012, earned an average salary of $3,213,479, with a standard deviation of $1,451,308. Does the average salary of the Diamondbacks players differ from that of all players in the National League? What statistical analysis is used to answer this question?
z test
The average salary for all 27 Arizona Diamondbacks in the 2012 baseball season was $2,653,029, with standard deviation of $2,587,139. The population, all National League baseball players in 2012, earned an average salary of $3,213,479, with standard deviation of $1,451,308. Does the average salary of the Diamondbacks players differ from that of all players in the National League? What statistical analysis is used to answer this question?
z test
What kind of correlation would one expect to find between the results of two dice thrown simultaneously?
zero
the symbol for the population mean is:
μ
the mean of the population is represented by the symbol ____, and the mean of the sample is represented by the symbol_____.
μ, M