Statistics 5

±2.145

A researcher matched 30 participants on intelligence (hence 15 pairs of participants), and then compared differences in emotional responsiveness to two experimental stimuli between each pair. For this test, what are the critical values, assuming a two-tailed test at a .05 level of significance? ±2.042 ±2.045 ±2.131 ±2.145

matched samples pattern

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

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

Which of the following summarizes a t test that was significant and associated with a large effect size? t(22) = 3.02, p < .05, d = .36 t(12) = 2.95, p < .05, d = .82 t(60) = 1.76, p > .05, d = .45 t(30) = 1.03, p > .05, d = .20

two-independent-sample t test

A researcher compares differences in mean health scores between students at two local high schools. Assuming that the population variance is unknown, what type of t test is appropriate for this study? There is not enough information to answer this question. one-sample t test two-independent-sample t test

Crying time was significantly reduced among infants given the sucrose solution prior to a heel prick.

A researcher records the crying time (in minutes) of infants given oral administration of sucrose (n = 12) or tap water (n = 16) prior to a heel prick. The mean crying time in the sucrose group was 3.3 ± 2.4 (M ± SD) min; in the tap water group, it was 7.3 ± 1.6 (M ± SD) min. If the null hypothesis is that there is no difference in crying time, then what is the decision for this test? Crying time was significantly reduced among infants given the water solution prior to a heel prick. Crying time was not reduced among infants given the sucrose solution prior to a heel prick. Crying time was significantly reduced among infants given the sucrose solution prior to a heel prick. Crying time was the same in both groups.

between subject factor

A type of factor in which different participants are observed in each group, or at each level of the factor, is called ______ within-subjects factor mixed factor between-subjects factor repeated measures factor

have no effect on

All other things being equal, reducing the level of significance from .05 to .01 will ______ the value of the test statistic for a related-samples t test. decrease have no effect on increase

it increases the variability measured in a study

Each of the following is an advantage for using the related-samples design, except ______. it can be more practical it increases the variability measured in a study it minimizes standard error it increases the power of a research design

standard error

Each of the following is an estimate of error for a t test, except ______. estimated standard error for the difference standard error estimated standard error estimated standard error for difference scores

similarly

Eta-squared is computed ______ for the one-sample, and the two-independent-sample t tests. similarly differently infinitely semantically

90% CI 3.2, 10.8

In a sample of 17 participants, a researcher estimates the 90% CI for a sample with a mean of MD = 7 and an estimated standard error for the difference scores (sMD) of 2.2. What is the confidence interval at this level of confidence? 90% CI 2.4, 11.6 90% CI 4.8, 9.2 There is not enough information to answer this question. 90% CI 3.2, 10.8

±2.093

State the critical value(s) for a t test using a two-tailed test at a .05 level of significance: t(20). ±1.725 ±2.093 ±0.687 Correct Answer ±2.086

overlap

The more that scores in each group ______, the larger the error variance. do not overlap are dependent overlap are significant

Researcher A

Two researchers (A and B) compute a two-independent-sample t test. For both tests, the standard error is the same, but the mean difference between the groups is larger for Researcher A. Which test is more likely to result in a decision to reject the null hypothesis? Researcher A Researcher B The likelihood is the same for both researchers. There is not enough information to answer this question.

related samples t test

A professor compares scores on a competency exam among students at two times during a single semester. What type of t test is most appropriate for this study? one-sample t test related-samples t test two-independent-sample t test There is not enough information to answer this question.

d = 0.62 (medium effect)

A professor computes the mean difference in exam scores before and after a lecture as 9.0 ± 14.5 (MD ± sD), and this difference was significant. What is the effect size for this result using estimated Cohen's d? d = 1.61 (large effect) d = 0.62 (large effect) d = 0.62 (medium effect) d = 1.61 (medium effect)

two-independent-sample t test

A researcher conducts a study measuring differences in brain activity among rats placed on either a continuous or intermittent reward schedule. Assuming that the population variance in unknown, what t test is appropriate for this study? one-sample t test two-independent-sample t test There is not enough information to answer the question

12% of the variability in marketing effectiveness can be accounted for by the new marketing strategy.

A researcher reports that the effectiveness of a new marketing campaign significantly increased sales compared with the previous campaign strategy, t(49) = 2.562, p < .05. Use eta-squared to interpret the effect size for this result. Marketing effectiveness shifted 0.12 standard deviations above the mean in the population. 12% of the standard error can be accounted for by the effectiveness of the marketing strategy. There is not enough information to answer this question. 12% of the variability in marketing effectiveness can be accounted for by the new marketing strategy.

The critical value decreases

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)? The critical value increases. The critical value does not change. The critical value decreases. It depends on the value of the test statistic.

be more practical

The related-samples design can ______. eliminate within groups error be more practical increase standard error reduce power