Stats Ch 10

A researcher studies 45 volunteer citizens from a small community and asks them about the amount of caffeine (in milligrams) they ingest before and after lunch each day, a phenomenon assumed to be normally distributed. Which assumption for the paired-samples t test is NOT met in this research design? a. The dependent variable is a scale variable. b. Participants are randomly selected. c. The population is normally distributed. d. All the assumptions are met.

b. Participants are randomly selected.

A paired-samples t test is reported as t(15) = 0.918, p > 0.05, d = 0.17. What is the effect size for this statistical test? a. There is no effect size reported. b. This is a small effect. c. This is a medium effect. d. This is a large effect.

b. This is a small effect.

When conducting a paired-samples t test, one can assess the practical importance of the obtained results by calculating: a. a hypothesis test. b. an effect size measure. c. post-hoc tests. d. a confidence interval.

b. an effect size measure.

A researcher is worried that performance on an aptitude test will improve simply because of repeat exposure to the instrument, which will cloud his ability to assess the impact of two unique educational interventions he wants to study. To help remove the effect of repeated exposure, the researcher could use: a. repeated measures. b. counterbalancing. c. a within-groups design. d. a single-sample t test.

b. counterbalancing.

The denominator (bottom portion) of the ratio for calculating the dependent-samples t statistic is the: a. pooled variance. b. estimated standard error of the distribution of mean difference scores. c. estimated standard error of the sampling distribution of the mean. d. estimated standard deviation

b. estimated standard error of the distribution of mean difference scores.

A paired-samples test is reported as t(18) = 1.73. What decision about this test should be made, assuming a two-tailed hypothesis test with a p level of 0.05? a. fail to reject the research hypothesis b. fail to reject the null hypothesis c. reject the null hypothesis d. reject the research hypothesis

b. fail to reject the null hypothesis

What would be the decision for a two-tailed paired-samples t test where the confidence interval was determined to be [-3.45, 2.61]? a. reject the null hypothesis b. fail to reject the null hypothesis c. reject the research hypothesis d. fail to reject the research hypothesis

b. fail to reject the null hypothesis

What would be the decision for a two-tailed paired-samples t test where the t statistic is -2.67, with cutoffs of ±2.776? a. reject the null hypothesis b. fail to reject the null hypothesis c. reject the research hypothesis d. fail to reject the research hypothesis

b. fail to reject the null hypothesis

What would be the decision for a two-tailed paired-samples t test where the t statistic is 2.67, with cutoffs of ±2.776? a. reject the null hypothesis b. fail to reject the null hypothesis c. reject the research hypothesis d. fail to reject the research hypothesis

b. fail to reject the null hypothesis

What would be the decision for the following paired-samples t test: t(24) = 1.11, p > 0.05? a. reject the null hypothesis b. fail to reject the null hypothesis c. reject the research hypothesis d. fail to reject the research hypothesis

b. fail to reject the null hypothesis

Assume the following for a paired-samples t test: N = 19, Mdifference = 13.19, s = 22.3. What is the size of the effect? a. small b. medium c. large d. no effect

b. medium

Another name for a dependent-samples t test is the _____ t test. a. single-sample b. paired-samples c. independent-samples d. no-sample

b. paired-samples

The formula for calculating effect sizes for the paired-samples t test replaces the _____ symbol used in the t statistics with the _____ symbol. a. s; sM b. sM; s c. μ; μM d. μM; μ

b. sM; s

The final step in calculating a confidence interval for a paired-samples t test is to convert the: a. effect sizes to t scores. b. t statistics into raw mean differences. c. t statistics into z statistics. d. z statistics into t statistics.

b. t statistics into raw mean differences.

What is the formula for the paired-samples t test?

c. (Mdifferernce - 0)/Sm

In a paired-samples t test, the null hypothesis posits that the mean of the comparison distribution is: a. the same as the mean of the population. b. 1. c. 0. d. -1.

c. 0.

Assume the following for a paired-samples t test: N = 19, Mdifference = 13.19, s = 22.3. What is the effect size using Cohen's d? a. 0.22 b. 0.41 c. 0.59 d. 2.58

c. 0.59

Assume the following for a paired-samples t test: N = 12, Mdifference = 635.65, s = 608.50. What is the effect size statistic? a. 0.02 b. 0.56 c. 1.04 d. 2.31

c. 1.04

Assume the following for a paired-samples t test: N = 12, Mdifference = 635.65, s = 608.50. What is the t statistic? a. 183.50 b. 52.97 c. 3.62 d. 1.04

c. 3.62

For the following data, what is the standard error of the difference scores? Before. After 110. 103 98. 104 89. 97 114. 127 a. 8.52 b. 5.00 c. 4.26 d. 1.17

c. 4.26

What is the standard error for the paired-samples t test for the following difference scores: -2, -19, +17, -22, -6? a. -6.40 b. -0.92 c. 6.96 d. 15.57

c. 6.96

A researcher investigates whether the extent to which people care about keeping their house clean and neat changes if they are given new things in that home. He follows eight families that were selected to receive home makeovers, assessing their cleanliness before the makeover and after. Given the confidence interval [-1.26, 0.95], what decision about the hypothesis should be made. a. Reject the null hypothesis because the confidence interval includes the null hypothesized value. b. Reject the null hypothesis and conclude that cleanliness did not change as a result of the manipulation. c. Fail to reject the null hypothesis because 0 falls in the confidence interval. d. Fail to reject the null hypothesis because the confidence interval has positive and negative values.

c. Fail to reject the null hypothesis because 0 falls in the confidence interval.

The formula for the degrees of freedom for the dependent-samples t test is: a. N. b. dfX + dfY. c. N - 1. d. (N - 1)(N - 1).

c. N - 1.

Which of these is NOT an assumption of the paired-samples t test? a. The dependent variable is a scale variable. b. Participants are randomly selected. c. There are fewer than 30 sample data. d. The population is normally distributed.

c. There are fewer than 30 sample data.

Assume the following for a paired-samples t test: N = 19, Mdifference = 13.19, s = 22.3. What is the 95 percent confidence interval for a two-tailed test? a. [11.09, 15.29] b. [8.07, 18.31] c. [2.44, 23.94] d. [-10.76, 10.76]

c. [2.44, 23.94]

The American Psychological Association encourages researchers to report _____ for paired-samples t tests. a. effect sizes only b. confidence intervals only c. both effect sizes and confidence intervals d. either effect sizes or confidence intervals

c. both effect sizes and confidence intervals

One of the first steps in calculating the dependent-samples t statistic is: a. counterbalancing the order of the calculations. b. finding the variance for each of the measured variables and then pooling them. c. creating a difference score for each participant in the sample. d. averaging the scores on each of the measured variables and finding the difference between those means.

c. creating a difference score for each participant in the sample.

Assume the following for a paired-samples t test: N = 12, Mdifference = 635.65, s = 608.50. What is the size of the effect? a. small b. medium c. large d. no effect

c. large

Twenty people participate in a weight-loss program for two months. Their weights after the two months are compared to their starting weights. What kind of mean difference might be expected if the null hypothesis is true for a paired-samples t test? a. a loss of pounds, on average, showing the effectiveness of the program b. a negative mean difference, indicating significant weight loss c. no change in weight or weight gain, indicating that the program does not work d. weight loss, indicating that the program does not work

c. no change in weight or weight gain, indicating that the program does not work

In a paired-samples t test, a possible confounding variable that can occur as a result of the within-groups design is: a. counterbalancing. b. repeated measures. c. order effects. d. error effects.

c. order effects.

In a within-groups design with two groups, the appropriate hypothesis test is a(n): a. single-sample t test. b. two-way analysis of variance. c. paired-samples t test. d. independent-samples t test.

c. paired-samples t test.

The critical cutoffs for a two-tailed, paired-samples t test with seven participants at a p level of 0.01 are: a. -2.447 and 2.447. b. -2.998 and 2.998. c. -3.143 and 3.143. d. -3.708 and 3.708.

d. -3.708 and 3.708.

For the following data, what is the paired-samples t test? Before. After 110. 103 98 104 89. 97 114. 127 a. 8.52 b. 5.00 c. 4.26 d. 1.17

d. 1.17

What is the standard error of the difference scores for a paired-samples t test for the following difference scores: 8, 3, 4.5, 7, 11.1, 9? a. 7.10 b. 5.86 c. 2.97 d. 1.21

d. 1.21

A researcher studies 45 volunteer citizens from a small community and asks them about the amount of caffeine (in milligrams) they ingest before and after lunch each day. Two measures are taken from each participant for a total of 90 data points. The degrees of freedom for this paired-samples study are: a. 90. b. 89. c. 45. d. 44.

d. 44.

The formula for the research hypothesis for a paired-samples t test is: a. H0: μ1 = μ2. b. H0: μ1 ≠ μ2. c. H1: μ1 = μ2. d. H1: μ1 ≠ μ2.

d. H1: μ1 ≠ μ2.

What is the 95 percent confidence interval for a two-tailed test for the following difference scores: -2, -19, +17, -22, -6? a. [-1.17, 13.22] b. [-13.36, 0.56] c. [-15.25, 7.38] d. [-25.72, 12.92]

d. [-25.72, 12.92]

When conducting a paired-samples t test, one can assess the research hypothesis and get a range of mean differences that could be expected in the future using: a. a hypothesis test. b. an effect size measure. c. post-hoc tests. d. a confidence interval.

d. a confidence interval.

A psychologist is interested in whether working memory is influenced by sleep loss. The psychologist administers a measure of working memory to a group of subjects at 8 A.M. on Day One of the study and then again at 8 A.M. on Day Two of the study, after keeping the subjects awake the entire night. Does sleep loss affect working memory? What statistical analysis we should be performed to answer this question? a. single-sample t test b. z test c. standard deviation analysis d. dependent-samples t test

d. dependent-samples t test

A study by Bettmann (2007) published in the Journal of the American Psychoanalytic Association assessed whether the attachment relationships between adolescents and their parents change as a result of a residential wilderness treatment experience for the adolescents. Participants completed the Adolescent Attachment Questionnaire at the start and at the end of the wilderness program. Which statistical test should be used to determine whether the wilderness treatment affected attachment relationships? a. single-sample t test b. z test c. effect size test d. dependent-samples t test

d. dependent-samples t test

A researcher studies 45 volunteer citizens from a small community and asks them about the amount of caffeine (in milligrams) they ingest before and after lunch each day. The null hypothesis for this paired-samples study could be: a. more caffeine is ingested before lunch. b. more caffeine is ingested after lunch. c. there is a difference between the amount of caffeine ingested before and after lunch. d. there is no difference between the amount of caffeine ingested before and after lunch.

d. there is no difference between the amount of caffeine ingested before and after lunch.

A clinical researcher was interested in determining whether her interventions were effective in minimizing depression symptoms among participants. To assess the effectiveness of the treatment program, she administered a depression inventory prior to treatment and after treatment. She hypothesized that depression scores would be lower at time two compared to time one. She then compared the mean differences between the two groups and found that the treatment was effective. The dependent variable in this study is: a. depression scores. b. gender. c. age. d. time.

a. depression scores.

In a paired-samples test, the comparison distribution is a distribution of: a. mean difference scores. b. raw score differences. c. median distribution scores. d. means.

a. mean difference scores.

The comparison distribution in a paired-samples t test is a distribution of: a. mean difference scores. b. differences between means. c. means. d. scores.

a. mean difference scores.

A clinical researcher was interested in determining whether her interventions were effective in minimizing depression symptoms among participants. To assess the effectiveness of the treatment program, she administered a depression inventory prior to treatment and after treatment. She hypothesized that depression scores would be lower at time two compared to time one. She then compared the mean differences between the two groups and found that the treatment was effective. The researcher's hypothesis is: a. one-tailed. b. two-tailed. c. not supported. d. supported by null hypothesis.

a. one-tailed.

The possible threat of participants having experience with the variables in a within-groups design when they experience those variables for the second time is known as: a. order effects. b. counterbalancing. c. repeated effects. d. stimulus repeating.

a. order effects.

What would be the decision for a two-tailed paired-samples t test where the confidence interval was determined to be [-3.45, -0.61]? a. reject the null hypothesis b. fail to reject the null hypothesis c. reject the research hypothesis d. fail to reject the research hypothesis

a. reject the null hypothesis

What would be the decision for a two-tailed paired-samples t test where the confidence interval was determined to be [1.34, 6.45]? a. reject the null hypothesis b. fail to reject the null hypothesis c. reject the research hypothesis d. fail to reject the research hypothesis

a. reject the null hypothesis

What would be the decision for a two-tailed paired-samples t test where the t statistic is -4.67, with cutoffs of ±2.776? a. reject the null hypothesis b. fail to reject the null hypothesis c. reject the research hypothesis d. fail to reject the research hypothesis

a. reject the null hypothesis

What would be the decision for a two-tailed paired-samples t test where the t statistic is 4.67, with cutoffs of ±2.776? a. reject the null hypothesis b. fail to reject the null hypothesis c. reject the research hypothesis d. fail to reject the research hypothesis

a. reject the null hypothesis

What would be the decision for the following paired-samples t test: t(24) = 4.11, p < 0.05? a. reject the null hypothesis b. fail to reject the null hypothesis c. reject the research hypothesis d. fail to reject the research hypothesis

a. reject the null hypothesis

The correct formula for effect size using Cohen's d for a paired-samples t test is: a. (M - μ)/s + σ. b. (M - μ)/s. c. (X - μ)/s. d. (σ - μ)/s.

b. (M - μ)/s.

What is the paired-samples t test for the following difference scores: -2, -19, +17, -22, -6? a. -6.40 b. -0.92 c. 6.96 d. 15.57

b. -0.92

The critical cutoff(s) for a one-tailed, paired-samples t test with 16 participants at a p level of 0.05 is (are): a. -1.746 or 1.746. b. -1.753 or 1.753. c. -2.120 and 2.120. d. -2.132 and 2.132.

b. -1.753 or 1.753.

Assume the following for a paired-samples t test: N = 9, Mdifference = 13.19, s = 22.3. What is the t statistic? a. 0.59 b. 1.77 c. 4.40 d. 7.43

b. 1.77

For the following data, what is the mean of the difference scores? Before. After 110. 103 98. 104 89. 97 114. 127 a. 8.52 b. 5.00 c. 4.26 d. 1.17

b. 5.00

What is the paired-samples t test for the following difference scores: 8, 3, 4.5, 7, 11.1, 9? a. 7.10 b. 5.86 c. 2.97 d. 1.21

b. 5.86

The critical cutoff(s) for a two-tailed, paired-samples t test with 23 participants at a p level of 0.05 is (are): a. -2.074 and 2.074. b. -2.069 or 2.069. c. -1.717 or 1.717. d. -1.714 and 1.714.

a. -2.074 and 2.074.

What is the mean difference of the following difference scores: -2, -19, +17, -22, -6? a. -6.40 b. -0.92 c. 6.96 d. 15.57

a. -6.40

Twenty college students experience the effects of alcohol on reaction time. They perform very basic timed responses in a driving simulator both before and after consuming several alcoholic beverages. The researcher collects a reaction time result for each of the 20 students before and after intoxication, for a total of 40 measures. What are the degrees of freedom for this study? a. 19 b. 20 c. 39 d. 40

a. 19

What is the mean of the difference scores for the following difference scores: 8, 3, 4.5, 7, 11.1, 9? a. 7.10 b. 5.86 c. 2.97 d. 1.21

a. 7.10

The formula for the null hypothesis for a paired-samples t test is: a. H0: μ1 = μ2. b. H0: μ1 ≠ μ2. c. H1: μ1 = μ2. d. H1: μ1 ≠ μ2.

a. H0: μ1 = μ2.

A researcher is worried that performance on an aptitude test will improve simply because of repeat exposure to the instrument, which will cloud his ability to assess the impact of two unique educational interventions he wants to study (Program A and Program B). Which of these design options includes counterbalancing? a. He could vary the order of the educational interventions such that half of the participants experience Program A first and the other half experience Program B first. b. He could recruit different participants for each educational program. c. Participants could complete Program A and then wait several months before completing Program B. d. The weaker of the two programs could be administered first so that improvement would still be measurable.

a. He could vary the order of the educational interventions such that half of the participants experience Program A first and the other half experience Program B first.

A researcher investigates whether chocolate affects mood. She recruits college students to take a mood inventory, ingest a quarter pound of chocolate, and then complete the mood inventory again. Given the confidence interval [2.34, 5.41], what decision about the hypothesis should be made? a. Reject the null hypothesis and conclude that chocolate affected mood because 0, or no effect, does not fall within the confidence interval. b. Reject the null hypothesis and conclude chocolate lowers affect because the confidence interval includes small numbers. c. Fail to reject the null hypothesis because the confidence interval is positive. d. Fail to reject the null hypothesis and conclude the effect size is small for this study.

a. Reject the null hypothesis and conclude that chocolate affected mood because 0, or no effect, does not fall within the confidence interval.

Twenty college students experience the effects of alcohol on reaction time. They perform very basic timed responses in a driving simulator both before and after consuming several alcoholic beverages. The researcher collects a reaction-time result for each of the 20 students before and after intoxication, for a total of 40 measures. What is the null hypothesis for this paired-samples study? a. There is no difference in reaction time before and after consuming alcohol. b. Reaction time slows with alcohol consumption. c. There is a difference in reaction time before and after consuming alcohol. d. Reaction time quickens with alcohol consumption.

a. There is no difference in reaction time before and after consuming alcohol.

Assume the following for a paired-samples t test: N = 9, Mdifference = 101.4, s = 450.2. What is the 90 percent confidence interval for a two-tailed test? a. [-177.72, 380.52] b. [-101.4, 101.4] c. [-48.67, 251.47] d. [99.54, 103.26]

a. [-177.72, 380.52]

When conducting a paired-samples t test, the sample mean difference is compared to: a. a distribution of mean differences. b. sample means. c. differences between means. d. the t distribution.

a. a distribution of mean differences.

According to the null hypothesis, the mean difference for the comparison distribution in a paired-samples t test is: a. always 0. b. sometimes 0. c. always 1. d. sometimes 1.

a. always 0.