Exam 2
When a researcher uses a conveience sample instead of a random ample to conduct a study, the researcher is limiting the study's
generalizability
As sample size decreases, the shape of the t distribution:
gets progressively wider
When data cover a huge range, such as populations of countries, it makes sens to construct a:
grouped frequency table
One of the assumptions for ANOVA is that the variances between groups are equal; we refer to this as:
homoscedasticity
What is NOT a name for one of the four sections common in a research report?
hypotheses
Under what circumstances can a very small treatment effect be statistically significant?
if the sample size is large and the sample variance is small
Which is NOT a way to increase statistical power?
increase the standard deviation
When conducting a study of gender differences, we have to employ a(n)
independent- samples t test
A biology instructor is interested in determining the average height of students in her class. The instructor finds that, on average, students in her biology class are 70 inches. Is this statement an example of a descriptive statistic or an inferential statistic?
inferential
Professor Henderson is interested in determining the average height for the entire population of college students. She wants to know how her class compares to the population of all college students. She finds that the average height for the population is 71.3 inches. Is this statement an example of a descriptive statistic or an inferential statistic?
inferential
In the simple linear regression formula, the ___ is the predicted value for y when x is equal to 0 the point at which the line crosses the y-axis.
intercept
The scale of measurement for temperature is
interval
A(n)_____ is based on our sample statistic; it conveys the range of sample statistics we could expect if we conducted repeated hypothesis tests using samples from the same population.
interval estimate
In which section of a research paper do we describe how we planned the sample size, preregistered the study, created the data analysis plan, and selected relevant psychometric statistics?
introduction
A repeated-measures analysis of variance produces SStotal = 40 and SSwithin = 10. For this analysis, what is SSbetween?
it cannot be determined from the available information
When N is small (less than 30), how does the shape of the tdistribution compare to the normal distribution?
it is flatter and more spread out than the normal distribution
Regression to the mean occurs because extreme scores tend to become
less extreme
The regression line is also known as the
line of best fit
_____ refers to the means of the rows and the columns in a table that shows the cells of a study with a two-way ANOVA design.
marginal mean
Emma wants to calculate her current quiz grade for her business class. She adds together her scores for quizzes 1-10. She then divides this total by 10, the number of quizzes. Emma has just calculated her quiz
mean
Researchers examined the effects of caffeine on students' test performance and found that caffeine significantly increased test performance. When they examined the effect size, they found that Cohen's d was 0.4. Based on convention, this effect is considered:
medium
The statement that postulates that there is no difference between populations (or that the difference is in a direction opposite from that anticipated by the researcher) is called the:
null hypothesis
A z score is defined as the:
number of standard deviations a particular score is from the mean
Which of the following statements is a correctly worded null hypothesis for an independent-samples t test
on average; women categorize the same percentage of cartoons as being funny as men do
A researcher hypothesizes that there is a significant relationship between meditation and stress levels. Specifically, he hypothesizes that as a person meditates more, stress levels will decrease. This example best illustrates what type of hypothesis test?
one-tailed test
Which test is NOT one that has a nominal IV and a scale DV?
one-way within-groups ANOVA
If you have one nominal IV with three groups where participants are in every group, and a scale DV, which test would you use?
one-way within-groups anova
A simple regression allows us to use _____ independent variable(s), while a multiple regression analysis allows us to use _____ independent variables.
one; two or more
When reporting the results of a research study, you should include:
only statistically significant findings
The fact that a research participant encounters the dependent variable twice in a within-groups design means that we have to be concerned about
order effects
An independent variable that makes a separate and distinct contribution in the prediction of a dependent variable, as compared with another variable, is called a(n) _____ variable.
orthogonal
An unethical practice that is used to increase the chances of achieving a statistically significant result is:
p-hacking
If you have one nominal IV with two groups from two samples where participants are in only one of the two groups, and a scale DV, which test would you use?
paired-samples t test
A probability multiplied by 100 is called a:
percentage
A(n) _____ is a summary statistic from a sample; it is a single number that serves as an estimate of the population parameter.
point estimate
The weighted average of the two estimates of variance (one from each sample) that are calculated when conducting an independent-samples t test is referred to as:
pooled variance
How do we calculate the interquartile range (IQR.
q3-q1
A correlation coefficient is a statistic that:
quantifies the relation between two variables
To find the effect size for an ANOVA, we calculate:
r2
Which of the following is NOT one of the three assumptions for hypothesis testing?
random assignment to levels of the independent variable
A sample in which every member of the population has an equal chance of being selected into the study is called a:
random sample
All of the following are among the six steps of hypothesis testing EXCEPT:
randomly selecting participants from the population
You are scheduled to visit your physician for a checkup. Your doctor performs a routine medical exam, which includes measuring your height and weight in addition to your blood pressure and temperature. The scale of measurement for weight is:
ratio
It is advantageous to use a within-groups ANOVA compared to a between-groups ANOVA because a within-groups ANOVA:
reduces error because the same participants contribute to each condition of the study
Refers to the tendency of scores that are particularly high or low to drift toward the mean over time
regression to the mean
A one-way within-groups ANOVA is also known as a:
repeated-measures ANOVA
It is hypothesized that there is a significant difference in anxiety levels between freshman men and women. This hypothesis best illustrates a:
research hypothesis
In which section of a research paper do we describe our analyses and findings from both traditional hypothesis testing and the new statistics?
results
The symbol used to designate the standard deviation when estimating from a sample is:
s
What type of graph is particularly useful for displaying a correlation?
scatterplot
The coefficient of determination is also known as:
simple linear regression
A(n) _____ is a type of t test in which we compare data from one sample to a population for which we know the mean but do not know the standard deviation.
single-sample t test
When calculating R2 (effect size) for the one-way within-groups ANOVA, we do not have to be concerned with the calculation for:
sswithin-
Nonparametric tests differ from parametric tests in that they are:
statistical tests that are not based on a set of assumptions about the population.
In comparison to the calculations for a one-way between-groups ANOVA, a one-way within-groups ANOVA is unique in that we must calculate a _____ sum of squares.
subjects
When we have rejected the null hypothesis for a chi-square test of independence, we need to examine _____ for each cell to determine where there are significant differences.
the adjusted standardized residuals
A one-way within-groups ANOVA is used when all of the following are true EXCEPT:
the dependent variable is nominal
The 95% confidence interval for MX - MY does not include 0. If H0: mX - mY = 0 were now being tested:
the difference mx-my would be significant at the 0.05 level
How does a distribution of sample means differ from a distribution of raw scores?
the distribution of means is more tightly packed
In a repeated-measures analysis of variance, how does the magnitude of the mean differences from one treatment to another contribute to the F ratio?
the mean differences add to the numerator of the f ratio
When constructing a histogram for data in a grouped frequency table, we have to calculate:
the midpoint for each interval
When computing our chi-square statistic, we calculate the difference between which two values?
the observed and expected frequencies
A sports psychologist developed a program to improve a team's playing ability. The sports psychologist measured each student's playing ability before and after his program to determine whether students would play better. He found that, after his program, students played significantly better. However, many students later reported that they had also begun consuming more fruits and vegetables within the same time frame to help them play better. In this example, what is the independent variable?
the program developed by the sports psychologist
Which of the following is NOT an example of a measure of central tendency
the range
A distribution of scores, drawn from a normal population, will more closely resemble a normal curve as:
the sample size increases
Suppose a researcher constructed a graph that reportedly showed that his weight-loss program is responsible for clients improved physical health. The clients who participated in the program volunteered to do so because they were motivated to lose weight and get healthier. Which technique for misleading with graphs does this example correspond to?
the sneaky sample lie
In a histogram, we label the x-axis with _____and the y-axis with _____.
the variable of interest; frequencies
A parameter is a number based on
the whole population
Professor Gonzalez completes a research study that shows that students who spend more time on social media tend to get a lower score on the daily pop quiz. Based on this conclusion, what can be said about the variables of "social media time" and "pop quiz score"?
there is a linear relationship
If you construct a graph of the means from a research study with a two-way factorial design and you see that the two lines in your graph intersect, this means that:
there is an interaction effect
A type of graph that plots a scale variable (on the y-axis) as it changes over an increment of time (plotted on the x-axis) is called a:
times series plot
A grouped frequency table is recommended for reporting the frequencies of a continuous variable.
true
A researcher using a nonparametric test is more likely to make a Type II error than a researcher who uses a parametric test.
true
A variable measured on an ordinal scale is never continuous.
true
If a hypothesis test using a sample of n = 15 scores produces a tstatistic of t = 2.15, then the correct decision is to reject the null hypothesis for a two-tailed test with an α of 0.05
true
If a researcher expects that a new teaching technique as compared to a standard teaching technique will be more effective for high school students than for younger middle school students, then the researcher is predicting an interaction between teaching technique and grade in school.
true
If the 90% confidence interval for µ is from 60 to 70, then the sample mean is M = 65.
true
If the degrees of freedom for an independent-samples t test is an odd number, then the two samples cannot be the same size.
true
If the z score falls at the 59th percentile, then 41% of scores fall above that value.
true
In a repeated-measures study, a small variance for the difference scores indicates that the treatment effect is consistent across participants.
true
It is impossible to make a Type II error when we reject the null hypothesis.
true
Paired-samples t tests are particularly well suited to research studies that examine learning or other changes that occur over time.
true
The first step in calculating a correlation coefficient is to examine a visual display of the data
true
The null hypothesis is stated in terms of the population even though the data come from a sample.
true
The null hypothesis predicts that there is no effect for our manipulation or that there is no difference between groups.
true
The scores for a very hard exam would probably form a positively skewed distribution.
true
The variance of a z distribution is always 1.
true
The z statistic is a mean score that has been standardized.
true
Two samples drawn from the same population will probably have different t statistics even if they are the same size and have the same mean.
true
Whenever a two-factor design results in a significant interaction, you should be cautious about interpreting the main effects because an interaction can distort, conceal, or exaggerate the main effects of the individual factors.
true
Which post hoc test is most commonly used for a one-way within-groups ANOVA?
tukey's hsd
If we reject the null hypothesis, but it was a mistake to do so, this action is called a:
type I error
When comparing three or more groups, we use ANOVA because conducting multiple t tests would result in an increased likelihood of a:
type I error
Which of the following terms best describes the following distribution of scores: 2, 3, 7, 7, 7, 7, 8, 10, 10, 15
unimodal
When a test accurately measures what it is intended to measure, we say that the test is:
valid
An ANOVA stands for analysis of:
variance
One difference between calculating an independent-samples t test and a paired-samples ttest is that with the independent-samples t test, we use the:
variance, not the standard deviation
Counterbalancing minimizes order effects by
varying the order of presentation of different levels of the independent variable from one participant to the next
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. it is necessary to estimate the standard deviation of the two samples to compare the two samples to each other
The research study conducted by the sports psychologist in the previous example is a:
within-groups research design
In a scatterplot, on which axes do we put our independent and dependent variables?
x-axis: independent variable; y-axis: dependent variable
One difference between the one-way between-groups ANOVA and the one-way within-groups ANOVA is that with the one-way within-groups ANOVA:
you have to be concerned about order effects
For a chi-square test of independence, we calculate the degrees of freedom using which formula?
-dfX2 = (krow - 1)(kcolumn- 1)
The mean of a z distribution is always
0
If a hypothesis test is found to have a power = 0.60, then what is the probability that the test will result in a Type II error?
0.40
George recently took an IQ test on which he received an IQ score of 115. If the population's mean IQ is 100 with a standard deviation of 15, what is George's z score?
1
Isla scored in the 85th percentile on a standardized test of reading ability. What is Isla's associated z score?
1.04
Which of the following distributions of scores has a range of 10
102,103, 104,105,106,112
A sample with Mdifference = 50 and a variance of s2= 25 has an estimated standard error of 1. How many scores are in the sample?
25
For a repeated-measures study comparing two treatments, a researcher obtains a sample of N = 16 difference scores with Mdifference = 6 and a variance of s2 = 64. What is the value for the tstatistic for these data?
3
How many Fstatistics are produced in a two-way ANOVA?
3
If Olivia received a z score of -1 for her performance on a standardized math test, approximately what percentage of scores are between Olivia's z score and the mean?
34.13%
What is the median for the following distribution of scores: 3, 4, 4, 11, 25?
4
If we obtain a z score of 1.5, what is our raw score for a given population mean of 500 and a standard deviation of 100?
650
A treatment is administered to a sample of N = 12 individuals selected from a population with a mean of µ = 70 and a standard deviation of σ = 8. After treatment, the effect size is measured by computing Cohen's d, and a value of d = 0.50 is obtained. Based on this information what is the mean for the treated sample
74
If Olivia received a z score of -1 for her performance on a standardized math test, approximately what percentage of scores are above her score?
84%
How is a correlation different from a regression analysis?
A regression enables us to make predictions, while a correlation describes relationships.
Which symbol is used for the standardized regression coefficient?
B
Harking is a practice in which a researcher:
Changes hypotheses to match the study's findngs
If you have only one nominal variable, which test would you use?
Chi-square test for goodness of fit
Based on the actual outcome of many, many trials the likelihood of an event occurring is called:
Expected relative- frequency proability
A distribution of z scores has a known mean and standard deviation. What are they?
Mean=0, SD=1
A z score is defined as the
Number of standard deviations a particular score is from the mean
_____ are inferential statistical analyses based on a set of assumptions about the population.
Parametric tests
When we calculate the proportionate reduction in error for a multiple regression, what symbol do we use?
R2
_____ is a measure of our ability to reject the null hypothesis given that the null hypothesis is false.
Statistical power
The assertion that a distribution of sample means approached a normal curve as sample size increases is called
The central limit theorem
When a research design involves two nominal variables, which nonparametric hypothesis test is used?
The chi-square test for independence
When conducting hypothesis testing for the pearson r correlation coefficient, we calculate degrees of freedom by subtracting 2 from the sample size. In pearson correlation, the sample size is
The number of participants
What is the difference between the z and t tests?
The t test uses the estimated standard error, whereas the z statistic uses the actual standard error of the population of means
What are three circumstances in which we commonly use a nonparametric test?
When the dependent variable is nominal, when either the independent variable or the dependent variable is ordinal, and when the sample size is small and an underlying population distribution is suspected to be skewed
When a researcher obtains a significant correlation between two variables in a study that she has conducted, it is appropriate to draw all of the following types of conclusions except:
Whether there is a cause-effect relationship between the two variables
An independent-samples t test is used with which type of research design?
a between-groups design
A normal distribution is a specific frequency distribution that has all of the following characteristics EXCEPT that:
a normal distribution is skewed
It is hypothesized that there will be a significant difference in aggression scores after caffeine consumption as compared to before caffeine consumption. This hypothesis best illustrates what type of t test
a paired-samples t test
If the treatment has a very small effect, then what is the likely outcome of a hypothesis test evaluating the treatment f the sample is very small
a type II error
A Pareto graph is defined as:
a type of bar graph in which the categories along the x-axis are ordered from the highest bar on the left to the lowest bar on the right.
The Pearson r correlation coefficient is a statistic that:
allows us to determine if there is a significant difference between two variables
Which type of graph would be best to construct if you have three levels of a nominal independent variable and one scale dependent variable?
bar graph
A _____ is a hypothesis test in which there are more than two samples and each sample is composed of different participants.
between-groups ANOVA
Caden is randomly assigned to participate in the experimental condition, and Lucas is randomly assigned to participate in the control condition of a research study. The research study must be a:
between-groups research design
What are two frequently used post hoc tests?
bonferroni and tukey
According to the textbook, all of these are steps involved in calculating a single-sample t test EXCEPT
calculate the z scores
For an independent-samples t test, which statistic do we use to measure effect size?
cohen's d
To calculate the effect size for a paired-samples t test, we use:
cohen's d
What measure of effect size assesses the difference between two means in terms of standard deviation?
cohen's d
What is the confounding variable in the previous example?
consuming more fruits and vegetables
What is the dependent variable in the previous example?
consuming more fruits and vegetables
Which of these is the correct formula for calculating effect size for a single-sample t test?
d=(m-u)/s
Dependent sampling generally results in a more powerful statistical test than does independent sampling because
dependent procedures reduce the variability in the sampling distribution
A paired-samples t test is also known as a(n):
dependent-samples t test
What is the formula for degrees of freedom for a single-sample t test?
df=n-1
What is the formula for the degrees of freedom for a between-groups ANOVA?
dfbetween=ngroups-1
When conducting a one-way within-groups ANOVA, what is the formula for degrees of freedom between?
dfbetween=ngroups-1
The formula for the degrees of freedom total is:
dftotal=dfx+dfy
When conducting a one-way within-groups ANOVA, what is the formula for degrees of freedom within?
dfwithin=(dfbetween)(df subjects)
The comparison distribution for an independent-samples t test is a distribution of:
differences between means
When using an independent samples t test, we have to create a:
distribution of differences between means
If you failed to reject the null hypothesis in your study, you should state in your research paper that you:
do not have evidence for your hypothesis
The easiest graph to interpret is a
dot plot
If you have two nominal IVs and a scale DV, which test would you use?
factorial anova?
A researcher reports the results of an ANOVA for a repeated-measures design as "F(2,12. = 6.87, p < 0.05." This study used a sample of N = 10 participants.
false
For a paired-samples t test, df = N1 + N2- 2
false
If the null hypothesis states that µ = 70 and a researcher obtains a sample M = 73 and s2 = 9, then Cohen's d = 0.33.
false
In contrast to correlation, regression allows the researcher to make a determination of cause- effect relations among variable
false
In general, the larger the value of the sample variance, the greater the likelihood of rejecting the null hypothesis.
false
Power is the probability that we will not make a Type I error.
false
Provided that our sample size is greater than 30, we can generalize the results of a study to most populations.
false
Random assignment is a critical component of correlational research.
false
The following F statistic indicates the ratio of two measures of variability. If the within-groups variance is much larger than the between-groups variance, we can infer that there is a significant difference between means. 𝐹=𝑏𝑒𝑡𝑤𝑒𝑒𝑛−𝑔𝑟𝑜𝑢𝑝𝑠 𝑣𝑎𝑟𝑖𝑎𝑛𝑐𝑒/𝑤𝑖𝑡ℎ𝑖𝑛−𝑔𝑟𝑜𝑢𝑝𝑠 𝑣𝑎𝑟𝑖𝑎𝑛𝑐𝑒
false
Two samples drawn from the same population will probably have similar t statistics if they are the same size and have the same mean.
false
We use Greek letters to symbolize values based on a sample of data
false
When calculating the IQR, the 50% percentile of the data set is identified as the mean.
false
When determining the critical value for an independent-samples t test, you use the degrees of freedom for the smaller sample.
false
When evaluating the magnitude of an effect size for a chi-square test, our criteria are based on the larger of the degrees of freedom for the rows and columns variables.
false
When performing a hypothesis test for correlation, we test against the null hypothesis, r=1.0
false