PSYCH104 Review - Chapter 7 (Hypothesis Testing and Power)

A z-score that is used for hypothesis testing is also called a ____. a. critical value b. critical region c. level of significance d. test statistic

d. test statistic

A treatment is administered to a sample selected from a population with a mean of m = 80 and a standard deviation of s = 10. After treatment, the effect size is measured by computing Cohen's d, and a value of d = 0.60 is obtained. Based on this information the mean for the treated sample is M = ____. a. 6 b. 86 c. 60 d. cannot be determined without additional information

b. 86

In a hypothesis test, a z-score value near zero ____. a. is probably in the critical region b. means that you should probably reject the null hypothesis c. None of the other options are correct. d. is strong evidence of a statistically significant effect

c. None of the other options are correct.

Which combination of factors will increase the chances of rejecting the null hypothesis? a. a large standard error and a large alpha level b. a small standard error and a small alpha level c. a small standard error and a large alpha level d. a large standard error and a small alpha level

c. a small standard error and a large alpha level

One assumption for a hypothesis test with z-scores is that the distribution of sample means ____. a. None of the other choices is correct. b. has a m the value of which is predicted by H1 c. is normal d. is based on less than 30 means

c. is normal

A Type I error is defined as a. failing to reject a true null hypothesis b. rejecting a false null hypothesis c. rejecting a true null hypothesis d. failing to reject a false null hypothesis

c. rejecting a true null hypothesis

If a treatment has a very small effect, then a hypothesis test evaluating the treatment effect is likely to ____. a. result in a Type I error b. correctly fail to reject the null hypothesis c. result in a Type II error d. correctly reject the null hypothesis

c. result in a Type II error

A research report summarizes the results of the hypothesis test by stating, "z = 2.13, p < .05." According to this report a. The null hypothesis was rejected and the probability of a Type I error is less than .05. b. The null hypothesis was not rejected and the probability of a Type II error is less than .05. c. The null hypothesis was rejected and the probability of a Type II error is less than .05. d. The null hypothesis was not rejected and the probability of a Type I error is less than .05.

a. The null hypothesis was rejected and the probability of a Type I error is less than .05.

In general, increasing the alpha level (for example from .01 to .05) will ____. a. increase the likelihood of rejecting the null hypothesis b. increase the standard error c. decrease the standard error d. decrease the likelihood of rejecting the null hypothesis

a. increase the likelihood of rejecting the null hypothesis

A researcher risks a Type I error ____. a. anytime the decision is "fail to reject H0" b. anytime H0 is rejected c. All of the other options are correct. d. anytime H1 is rejected

b. anytime H0 is rejected

The probability of a Type II error is expressed as ____. a. a b. b c. 1 - b d. 1 - a

b. b

In general, increasing the sample size (for example, from n = 4 to n = 50) will ____ the risk of a Type I error. (Assume alpha is held constant at .05.) a. increase b. have no influence on c. decrease

b. have no influence on

If the sample data produce a test statistic (z-score) that is in the critical region, then which of the following is the appropriate conclusion for the test? a. reject H1 b. reject H0 c. fail to reject H1 d. fail to reject H0

b. reject H0

The power of a statistical test is the probability of ____. a. supporting true null hypothesis b. rejecting a false null hypothesis c. supporting a false null hypothesis d. rejecting a true null hypothesis

b. rejecting a false null hypothesis

In hypothesis tests, standard error measures ____. a. the size of the treatment effect b. the amount of difference (or variability) between the sample mean and the population mean that is reasonable to expect just by chance c. variability among population means d. the size of the critical region

b. the amount of difference (or variability) between the sample mean and the population mean that is reasonable to expect just by chance

A researcher is predicting that a treatment will increase scores. If this treatment is evaluated using a directional hypothesis test, then the critical region for the test ____. a. cannot answer without knowing the value of the alpha level b. would be entirely in the right-hand tail of the distribution c. would be divided equally between the two tails of the distribution d. would be entirely in the left-hand tail of the distribution

b. would be entirely in the right-hand tail of the distribution

Which of the following will increase the power of a statistical test? Select one: a. change a from .05 to .01 b. change from a one-tailed test to a two-tailed test c. change the sample size from n = 100 to n = 25 d. None of the other options will increase power.

d. None of the other options will increase power.

A researcher administers a treatment to a sample of n = 25 participants and uses a hypothesis test to evaluate the effect of the treatment. The hypothesis test produces a z-score of z = 2.37. Assuming that the researcher is using a two-tailed test, a. The researcher should fail to reject H0 with either a = .05 or a = .01. b. The researcher should reject the null hypothesis with either a = .05 or a = .01. c. Cannot answer without additional information. d. The researcher should reject the null hypothesis with a = .05 but not with a = .01.

d. The researcher should reject the null hypothesis with a = .05 but not with a = .01.

A Type II error means that a researcher has ____. a. correctly concluded that a treatment has an effect b. correctly concluded that a treatment has no effect c. falsely concluded that a treatment has an effect d. falsely concluded that a treatment has no effect

d. falsely concluded that a treatment has no effect

In a hypothesis test, the critical region consists of ____. a. sample values that provide proof that H0 is true b. sample values that provide proof that H0 is false c. sample values that are highly likely to be obtained if H0 is true d. sample values that are very unlikely to be obtained if H0 is true

d. sample values that are very unlikely to be obtained if H0 is true