PSY 3204 Exam 3 Study Guide

Which measure of effect size is most commonly reported with a t test?

Cohen's d

A measure of the size of an effect in a population is called

Effect size

A researcher believes that increasing attention given to children will improve mean academic performance. Therefore, the alternative hypothesis should be

Mean academic performance will increase

For each p value stated below, what is the decision for each if α = 0.05? What is the decision for each if α = 0.01? : For p = 0.0003, what is the decision if α = 0.01?

Reject null hypothesis

For each p value stated below, what is the decision for each if α = 0.05? What is the decision for each if α = 0.01? : For p = 0.0003, what is the decision if α = 0.05?

Reject null hypothesis

A researcher conducts two t tests. Test 1 is a one-tailed test with a smaller sample size at a .05 level of significance. Test 2 is a one-tailed test with a larger sample size at a .05 level of significance. What do you know about the critical values for each test?

Test 2 is associated with smaller critical values.

The power of the decision-making process is

The likelihood of rejecting a false null hypothesis.

The first step to hypothesis testing requires that a researcher

State the hypothesis

The ______ is an inferential statistic used to determine the number of standard deviations in a t distribution that a sample mean deviates from the mean value or mean difference stated in the null hypothesis.

t statistic

Which of the following summarizes a t test that was significant and associated with a large effect size?

t(12) = 2.95, p < .05, d = .82

If the value of the test statistic is in the rejection region, then

- p < .05. - The value of the test statistic is larger than the critical value. - The decision is to reject the null hypothesis.

What is the typical level of significance for a hypothesis test in behavioral research?

.05

Alpha (α) is used to measure the error for decisions concerning true null hypotheses. What is beta (β) error used to measure?

Beta (β) error is a measure of error for decisions concerning false null hypotheses.

A key difference between a t statistic and a z statistic is that the standard error is ______ to compute a t statistic.

Estimated

Which of the following is NOT one of the four steps to hypothesis testing?

Evaluate the plan

A researcher records the number of distracters (such as noises) that preschool-aged children ignore while watching a popular Sunday morning cartoon show. Assuming that the population variance is unknown, what type of t test is appropriate for this study?

One-sample t test

You read about a study testing whether night shift workers sleep the recommended 8 hr/day. Assuming that the population variance of sleep (per day) is unknown, what type of t test is appropriate for this study?

One-sample t test

For each p value stated below, what is the decision for each if α = 0.05? What is the decision for each if α = 0.01? : For p = 0.0020, what is the decision if α = 0.01?

Reject null hypothesis

For each p value stated below, what is the decision for each if α = 0.05? What is the decision for each if α = 0.01? : For p = 0.0020, what is the decision if α = 0.05?

Reject null hypothesis

For each p value stated below, what is the decision for each if α = 0.05? What is the decision for each if α = 0.01? : For p = 0.0250, what is the decision if α = 0.05?

Reject null hypothesis

Two researchers (A and B) compute a one-sample t test. For both tests, the mean difference between the sample and value stated in the null hypothesis is 5, but the standard error is smaller for Researcher A. Which test is more likely to result in a decision to reject the null hypothesis?

Researcher A

For each p value stated below, what is the decision for each if α = 0.05? What is the decision for each if α = 0.01? : For p = 0.0250, what is the decision if α = 0.01?

Retain null hypothesis

For each p value stated below, what is the decision for each if α = 0.05? What is the decision for each if α = 0.01? : For p = 0.2000, what is the decision if α = 0.01?

Retain null hypothesis

For each p value stated below, what is the decision for each if α = 0.05? What is the decision for each if α = 0.01? : For p = 0.2000, what is the decision if α = 0.05?

Retain null hypothesis

The estimated standard error in the t statistic uses the ______ to estimate the ______ when the population variance is unknown.

Sample variance; population variance

Which of the following statements regarding the null hypothesis is true?

The null hypothesis always makes statements about a population parameter.

Will each of the following increase, decrease, or have no effect on the value of a test statistic for the one-independent sample z-test? : The difference between the sample mean and population mean is decreased.

This change will decrease the value of the test statistic.

Will each of the following increase, decrease, or have no effect on the value of a test statistic for the one-independent sample z-test? : The sample variance is doubled.

This change will have no effect on the value of the test statistic.

Will each of the following increase, decrease, or have no effect on the value of a test statistic for the one-independent sample z-test? : The population variance is decreased.

This change will increase the value of the test statistic.

Will each of the following increase, decrease, or have no effect on the value of a test statistic for the one-independent sample z-test? : The sample size is increased.

This change will increase the value of the test statistic.

A researcher obtains z = -6.45. What is the decision for a one-tailed test, upper-tail critical, at a .05 level of significance?

To retain the null hypothesis

A researcher directly controls for the probability of a ______, but does not directly control for the probability of a ______.

Type I Error; Type II Error

The probability of committing a Type I error is stated by ______; the probability of committing a Type II error is stated by ______.

alpha; beta

State the critical value(s) for the following two-tailed t test at a .05 level of significance: t(∞).

±1.96 and the same as for a two-tailed z test at a .05 level of significance

A professor gives an exam in which the mean score is 78 points. She gives another exam to test whether or not scores change. In this example, the null hypothesis is

μ = 78