Chapter 8: Hypothesis Testing
A researcher conducts two studies. Each study was a one-sample z test. Both studies placed the rejection region in both tails and measured the same sample mean. The alpha level in Study 1 was larger than the alpha level used in Study 2. Which study is associated with greater power to detect an effect?
Study 1
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
What three factors can be decreased to increase power? (Select all that apply.)
> beta error > population standard deviation > standard error
If the value of the test statistic is in the rejection region, then
> the decision is to reject the null hypothesis. > the value of the test statistic is larger than > p < .05. >the critical value. all of these.
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 measure of the size of an effect in a population is called
effect size.
The power of the decision-making process is
the likelihood of rejecting a false null hypothesis.
Given the following values: μ = 6.0, M = 7.6, n = 36, σ = 6, conduct a one-sample z test at a 0.05 level of significance. For a one-tailed test, upper-tail critical, what is the decision?
to retain the null hypothesis
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
A researcher reports the following result for a one-sample z test at a 0.05 level of significance: z = 1.88, p = 0.06 (d = 0.25). Is this result significant?
No, the decision is to retain the null hypothesis.
A researcher computes a test statistic and finds that the p value for this test is 0.03. What does this result mean?
There is a 3% likelihood of obtaining the test statistic value, if the null were true.
Will each of the following increase, decrease, or have no effect on the value of Cohen's d? (c) The population variance is increased.
This change will decrease the value of Cohen's d.
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? (c) The difference between the sample mean and population mean is decreased.
This change will decrease the value of the test statistic.
When a researcher decides to retain the null hypothesis because the rejection region was located in the wrong tail, this is called a
Type III error
The one-sample z test is a hypothesis test used to test hypotheses
concerning a single population with a known variance
Which of the following is not one of the four steps to hypothesis testing?
evaluate the plan
The first step to hypothesis testing requires that a researcher
state the hypotheses.
A professor finds that the average SAT score among all students attending his college is 1150 ± 150 (μ ± σ). He polls his class of 25 students and finds that the average SAT score is 1200. Suppose he computes a one-sample z test at a 0.05 level of significance. What is his decision?
to reject the null hypothesis for an upper-tailed test, but to retain the null hypothesis for a two-tailed test
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
What is the typical level of significance for a hypothesis test in behavioral research?
.05
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 Cohen's d? (a) The sample size is decreased.
This change will have no effect on the value of Cohen's d.
Will each of the following increase, decrease, or have no effect on the value of Cohen's d? (b) The sample variance is reduced.
This change will have no effect on the value of Cohen's d.
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? (d) 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 Cohen's d? (d) The difference between the sample and population mean is increased.
This change will increase the value of Cohen's d.
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? (a) The sample size is increased.
This change will increase the value of the test statistic
Will each of following increase, decrease, or have no effect on the value of a test statistic for the one-independent sample z-test? (b) The population variance is decreased.
This change will increase the value of the test statistic.
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.