Exam 2 Statistics for Behavior Science

"The minimum value of a statistic needed to reject the null hypothesis" is represented by a. sample size b. the absolute value c. alpha () d. the null hypothesis e. a critical value

critical value

For a sample of 18 participants, how many degrees of freedom (df) are there for a ttest for dependent means? a. 36 b. 35 c. 18 d. 17 e. 16

d. 17

For α = .05 (two-tailed), which of the following is an appropriate critical value? a. 1.711 b. 1.708 c. 2.060 d. 2.064 e. 2.069

d. 2.064

Computing a two-independent sample t test is appropriate when a. different participants are assigned to each group b. the population variance is unknown c. participants are observed one time d. all of the above

d. all of the above

In hypothesis testing, a researcher's decision a. is based on a probability b. depends on the level of significance for a hypothesis test c. can be to retain or reject the null hypothesis d. all of the above

d. all of the above

Based on the effect size conventions, d = 0.18 is a a. small effect size b. medium effect size c. large effect size

small effect size

A researcher comparing the means of two groups calculates the t-test for independent means and reports the following result: t(28) = 2.11, p <.05. This study consisted of a total of ____ participants. a. 14 b. 15 c. 28 d. 30

30

The process of hypothesis testing starts with the assumption that a. the null hypothesis is true b. the null hypothesis is false c. the alternative hypothesis is true d. we do not know whether the null hypothesis or the alternative hypothesis is true.

a. the null hypothesis is true

A Type II error occurs when a researcher ________. a. correctly rejects the null hypothesis b. says an effect does not exist when it in fact does c. falsely concludes that an effect exists d. rejects the null hypothesis when he should

b. says an effect does not exist when it in fact does

A study based on a sample of 13 participants calculates a value of 2.26 for the t-test for one mean. For alpha (α) = .05 (two-tailed), what is the appropriate way to present this analysis? a. t(11) = 2.26, p < .05 b. t(12) = 2.26, p < .05 c. t(12) = 2.26, p < .01 d. t(13) = 2.26, p < .01 e. t(13) = 2.26, p > .01

b. t(12) = 2.26, p < .05

A study tests the difference between 20 Democrats and 20 Republicans. In this example, the degrees of freedom (df) is equal to: a. 18 b. 19 c. 38 d. 39

c.38

When reporting the results of a one-sample z test using APA format, the ________ does not need to be reported. a. Test statistic b. p value c. effect size d. critical values

d. critical values

A study compares 5 Democrats and 5 Republicans and obtains a value of 2.27 for the t-statistic. For alpha (α) = .05 (two-tailed), which of the following is the correct way to present this analysis? a. t(10) = 2.27, p > .05 b. t(8) = 2.27, p < .05 c. t(9) = 2.27, p < .05 d. t(8) = 2.27, p > .05

d. t(8) = 2.27, p > .05

Which of the following things are not included in writing the results of the t-test in standard APA format? a. the degrees of freedom b. the obtained value of the statistic c. the level of significance d. the critical value(s)

d. the critical value(s)

You test the mean of a sample of 13 people and calculate a value of 2.10 for the tstatistic. For = .05 (two-tailed), which of the following decisions is most appropriate? a. do not reject null (p > .01) b. reject alternative (p < .05) c. accept alternative (p > .05) d. reject null (p < .05) e. do not reject null (p > .05)

do not reject null (p > .05)

Which type of error is used to compute the confidence interval for two independent samples selected from at least one population with an unknown variance? a. standard error b. estimated standard error c. estimated standard error for the difference d. estimated standard error for the difference scores

estimated standard error for the difference

A researcher conducts a study in which the same participants are observed across each level of the independent variable. If there are only two levels of the independent variable, then what type of t test is appropriate for this study? a. one-sample t test b. related samples t test c. two-independent sample t test d. There is not enough information to answer this question

related samples t test

A method for testing a claim about a parameter, using data measured in a sample, is called a. random sampling b. level of significance c. hypothesis testing d. guessing

Hypothesis Testing

The criteria for a decision regarding the value stated in a null hypothesis is set by the a. level of significance b. p value c. probability value d. both A and B

Level of significance

A Cohen's d value of .35 may be considered to be a ________ effect. a. small b. medium c. large d. nonsignificant

Medium

Using APA format, which value is typically given in parentheses when reporting the results for a t test? a. The degrees of freedom. b. The estimate for standard error. c. The value of the test statistic. d. The level of significance.

a. The degrees of freedom.

The one-sample z test is a hypothesis test used to test hypotheses a. concerning a single population with a known variance b. concerning at least one population c. concerning the variance in a population d. all of the above

a. concerning a single population with a known variance

A researcher records the time it takes (in seconds) for participants to respond (by pressing a key) to a familiar versus an unfamiliar word flashed onto a computer screen. In this study, the difference in response time for each participant is compared. The type of design described here is called a a. repeated measures design b. matched samples design c. both A and B

a. repeated measures design

A marriage counselor wishing to compare the values of married couples collects data from 10 husbands and their wives. Which type of statistical analysis should she use to analyze this data? a. t-test for dependent means b. t-test for one mean c. t-test for independent means d. z-test for one mean

a. t-test for dependent means

If the value of the test statistic is in the rejection region, then: a. p < .05 b. the decision is to reject the null hypothesis c. the value of the test statistic is larger than the critical value d. all of the above

all of the above

When the null hypothesis is not rejected, the results of the analysis may be described as ______ . a. "insignificant" b. "nonsignificant" c. "significant" d. "highly significant"

b. "nonsignificant"

A researcher conducts a study, but has low power to detect an effect. Which of the following is one way in which the research can increase power? a. Make the alpha level smaller. b. Increase the sample size. c. Study a population with a larger standard deviation. d. Conduct the study again with the same sample size.

b. Increase the sample size.

A researcher finds that the mean difference in productivity between employees working the morning shift (n = 16) and the night shift (n = 10) is 5.0 units, and the estimated standard error for the difference is 2.7 units. If the null hypothesis states that there is no difference in productivity, then is this result significant at a .05 level of significance? a. Yes, this result is significant. b. No, this result is not significant. c. There is not enough information to answer this question.

b. No, this result is not significant.

All other things being equal, as the sample size increases, what happens to the critical value for a related samples t test (or for any t test, for that matter)? a. The critical value increases. b. The critical value decreases. c. The critical value does not change. d. It depends on the value of the test statistic.

b. The critical value decreases.

An example of a Type I error is when a researcher concludes ________. a. an effect does not exist when it actually does b. an effect exists when it actually doesn't c. groups do not differ when they actually do d. groups are the same when they're actually different

b. an effect exists when it actually doesn't

A researcher conducts a study measuring 10 people before and after they watch a movie and obtains a value of 2.85 for the t-statistic. For a non-directional alternative hypothesis, which of the following is the correct way to present this analysis? a. t(10) = 2.85, p < .05 b. t(9) = 2.85, p < .05 c. t(18) = 2.85, p < .05 d. t(20) = 2.85, p < .01

b. t(9) = 2.85, p < .05

A researcher obtains z = -6.45. What is the decision for a one-tailed test, upper-tail critical, at a .05 level of significance? a. to reject the null hypothesis b. to retain the null hypothesis c. It depends on the sample size. d. There is not enough information to make a decision.

b. to retain the null hypothesis

A researcher obtains z = 1.45 for a one-sample z test. What is the decision for this test at a .05 level of significance? a. to reject the null hypothesis b. to retain the null hypothesis c. It depends on whether the test is one-tailed or two-tailed. d. There is not enough information to make a decision.

b. to retain the null hypothesis

A researcher records differences in ratings of emotion among participants watching either a drama or a romance film. Assuming that the population variance is unknown, what type of t test is appropriate for this study? a. one-sample t test b. two-independent sample t test c. two related samples t test d. There is not enough information to answer this question.

b. two-independent sample t test

Which of the following beliefs is the best example of a null hypothesis (H0)? a. "Men are smarter than women" b. "There is life on Mars" c. "Taking steroids does not help baseball players hit more home runs" d. "McDonald's hamburgers taste better than Burger King hamburgers

c. "Taking steroids does not help baseball players hit more home runs"

According to a recent study, the average college student owes $900 on their credit cards (Arano, 2006). Therefore, in this analysis, how could the null and alternative hypotheses be stated? a. H0: > 900; H1: < 900 b. H0: ≠ 900; H1: = 900 c. H0: = 900; H1: ≠ 900 d. H0: = 834.53; H1: ≠ 834.53

c. H0: = 900; H1: ≠ 900

The statement " > 8" is an example of a a. directional null hypothesis. b. non-directional null hypothesis. c. directional alternative hypothesis. d. non-directional alternative hypothes

c. directional alternative hypothesis.

A researcher finds that the mean income for her sample is $40,500 but the mean for the population from which the sample is drawn is believed to be $44,270. The difference between the two means can be attributed to: a. nonrandom sampling b. normal sampling c. luck d. sampling error

d. sampling error

Which of the following is a type of related samples design in which different participants are actually observed in each group, but treated statistically as if they are the same persons in each group. a. repeated measures design b. matched samples design c. pre-post design d. within-subjects design

matched samples design