Statistics Exam 4

The correct formula for Cohen's d for a single-sample t test is:

(M- µ)/s

What is the correct formula for Cohen's d for a paired-samples ttest?

(M- µ)/s

In an independent-samples t test, each group has N minus _____ degree(s) of freedom.

1

Psychology students took longer to complete a quiz when there was background music playing than when there was no background noise: t(19) = -4.01, p< 0.05. What is the sample size in this study?

20

If there are at least _____ participants in a study, it is likely that the normality assumption is met.

30

If dfbetween = 5, then there are _____ groups in the study.

6

To make comparisons between three or more groups for differences on a dependent variable, use a(n) _____.

ANOVA

To calculate the effect size for an independent-samples t test, use:

Cohen's d

A paired-samples t test is also known as a:

Dependent samples t-test

When comparing 3 or more groups, why can't we simply do multiple t tests instead of using ANOVA?

alpha gets inflated when doing multiple t-tests

An independent-samples t test is a _____ design

between groups

The F statistic is a ratio where we divide _____ by _____.

between-groups variance; within-groups variance

______ is a measure of effect size for an independent-samples t test.

cohen's d

Critical t values _____ as df _____.

decrease; increases

The symbol df stands for the:

degrees of freedom

The confidence interval for the independent-samples t test is centered around the _____.

difference between means

Effect size cannot be calculated for the independent-samples t test. (true or false)

false

Populations that have the same variance are referred to as heteroscedastic. (true or false)

false

The single-sample t test compares the mean of a sample to a population for which the mean and standard deviation are known. (true or false)

false

The standard deviation of the population is commonly used to estimate the standard deviation of the sample. (true or false)

false

The symbol s represents the standard deviation of the population. (true or false)

false

The ztest uses estimated standard error whereas the t test uses actual standard error. (true or false)

false

When computing standard error for the t test, divide s by the square root of N - 1. (true or false)

false

When computing the confidence interval for a t test, the cutoffs for the 95% interval are always the same. (true or false)

false

When reporting the test results for an independent-samples t test, Nis reported rather than degrees of freedom. (true or false)

false

When we conduct an ANOVA, the resulting F statistic can be negative or positive. (true or false)

false, positive including 0

The degrees of freedom for the single-sample t test is N - 2. (true or false)

false; N-1

The ttest is used when the standard deviation of the population is known. (true or false)

false; the ttest is used when mean and standard deviation are not known

Populations that have different variances are _____

heteroscedastic

Populations that have the same variance are _____.

homoscedastic

As the sample size increases, the degrees of freedom _____.

increases

A group of rats that received a steroid drug supplement ran faster than a group of rats that did not receive the drug supplement. Which type of statistical test should be used to analyze these results?

independent-samples t-test

In a(n) _____ t test, the samples of participants are from different groups, while in the a(n) _____ t test, participants are from the same group.

independent-samples; paired-samples

The final step in hypothesis testing for an independent-samples t test is:

making a decision and communicating your results.

An independent-samples t test compares differences between sample _____.

means

in an independent-samples t test, each participant is assigned to _____ group(s)

one

The hypothesis test used when there is one nominal independent variable with more than two levels and a scale-dependent variable is the _____ ANOVA.

one-way

The F distribution is

skewed right

The values on the F table under two samples are the same as those on the t table except that they are _____.

squared

The _____ indicates the distance of a sample mean from a population mean in terms of the estimated standard error.

t statistic

A confidence interval for a t test is centered around the mean of the sample. (true or false)

true

For a one-tailed t test, there is only one critical cutoff value. (true or false)

true

For a two-tailed t test, there are two critical cutoff values. (true or false)

true

For an independent-samples t test, the test statistic is compared to a distribution of differences between means. (true or false)

true

If the null hypothesis is true for a paired-samples t test, the mean of the distribution of mean differences is 0. (true or false)

true

Populations that have the same variance are referred to as homoscedastic. (true or false)

true

The F ratio measures two sources of variability: within-groups variance and between-groups variance. (true or false)

true

The appropriate APA format for the presentation of t test results appears as: t(19) = 3.13, p < 0.05. (true or false)

true

The equation for the paired-samples t test is the same as that for the single-samples t test except that the data are now difference scores. (true or false)

true

The independent-samples t test is considered a between-groups design. (true or false)

true

The more observations made, the more confident one can be in the estimate of the population. (true or false)

true

The paired-samples t test is also known as the dependent-samples ttest. (true or false)

true

The standard deviation of a sample can be used to estimate the standard deviation of a population. (true or false)

true

The ttest is a parametric statistical test that allows one to generalize what was learned about one sample to a larger population. (true or false)

true

When computing standard error for the t test, divide s by the square root of N. (true or false)

true

The major difference between the paired-samples t test and the single-samples ttest is that in the paired-samples t test:

we must create difference scores for every individual.

If there are more than two levels of the independent variable and the same participants were exposed to every level of the independent variable, then one should analyze the data with a(n) _____ ANOVA.

within-groups

researcher compares 3 different types of dog owners on some dependent measure. The variability among all the dog owners, regardless of group, is known as _____.

within-groups variability