Exam 3 Statistical Psychology Cassie Chandler

With α = .05, the two-tailed critical region for a t test using a sample of n = 20 participants would have boundaries of _____.

t = ±2.093

A sample of n = 25 scores produces a t statistic of t = +2.052. If the researcher is conducting a two-tailed hypothesis test, which of the following is the correct statistical decision?

The researcher should fail to reject the null hypothesis with either a = 0.05 or a = 0.01.

How does sample variance influence the estimated standard error and measures of effect size such as r² and Cohen’s d?

Larger sample variance increases the estimated standard error but decreases measures of effect size.

A sample is selected from a population with µ = 46, and a treatment is administered to the sample. After treatment, the sample mean is M = 48 with a sample variance of s² = 16. Based on this information, what is the value of Cohen’s d?

d = 0.50

If a sample of n = 22 scores is being used to make an 90% confidence interval estimate of the population mean (µ), which values of t should be used?

t = ±1.721

A research report states “t(18) = +3.00, p < 0.05.” For this test, r² = .33.

True

A research study has two samples, each with n = 7, and the two experimental treatments used in each sample are being compared using an independent-measures t statistic. What is the df value for the t statistic in this study?

df=12

Two samples, each with n = 5 scores, have a pooled variance of s²p = 40. What is the estimated standard error for the sample mean difference?

s(M1 - M2) = e

A researcher is examining whether daily yoga reduces stress. The researcher assigns n = 7 individuals to engage in daily yoga for three months and finds an average stress score of M = 16 with SS = 123 after three months for individuals in this group. A second group of n = 6 individuals assigned to a control group for the three months had a stress score of M = 21 with SS = 141. Which of the following is most consistent with the results of conducting a one-tailed independent-measures t test with α = .05?

t = -1.83 and reject the null hypothesis

A researcher reports t(18) = 5.30, p < 0.01, two tails for an independent-measures experiment. How many individuals participated in the entire experiment?

n = 20

An independent-measures research study uses two samples, each with n = 10 participants. If the data produce a t statistic of t = 2.015, which of the following is the correct decision for a two-tailed hypothesis test?

fail to reject the null hypothesis with either a = 0.05 or a = 0.01

A researcher conducts a repeated-measures study to evaluate the efficacy of therapy in increasing positive coping skills. The researcher examines positive coping skills before and after therapy with a sample of n = 6 participants and obtains a sample mean difference of M_D = 10 with an estimated standard error of s_MD = 4.78. Which of the following is the correct decision for a one-tailed hypothesis test in which therapy is expected to increase positive coping skills?

Reject the null hypothesis with a = 0.05 but not with a = 0.01

A repeated-measures study using a sample of n = 10 participants would produce a t statistic with df = _____.

9

A repeated-measures study comparing two treatments with a sample of n = 4 participants produces M_D = 3 with SS = 48 for the set of difference scores. What is the repeated-measures t statistic for these data?

t = + 1.50

When comparing more than two condition means, why should an analysis of variance be used instead of multiple t tests?

Using multiple t tests increases the risk of a Type I error

On average, which value is expected for the F-ratio if the null hypothesis is false?

an F value much greater than 1

A research study comparing three treatments with n = 5 in each treatment produces T₁ = 5, T₂ = 10, T₃ = 15, with SS₁ = 6, SS₂ = 9, SS₃ = 9, and SX² = 94. For this research study, what is SS_between?

SSbetween = 10

An ANOVA is used to evaluate the mean differences among three treatment conditions with a sample of n = 12 participants in each condition. For this research study, what is df_within?

dfwithin = 33

A researcher uses analysis of variance to test for mean differences among three treatments with a sample of n = 12 in each treatment. The F-ratio for this analysis would have which df values?

df = 2, 33

An independent-measures research study compares three treatment conditions using a sample of n = 5 in each condition. For this study, the three samples have SS₁ = 10, SS₂ = 20, and SS₃ = 15. Which value would be obtained for MS_within?

MSwithin = 3.75

A researcher uncovers that there is a significant interaction between the factor of marital status (i.e., married or non-married) and participant sex (i.e., male or female) regarding well-being among a sample with n = 6 participants in each condition. What would the critical value for the F-ratio be for a hypothesis test examining the difference in well-being between married men and women using an alpha level of α = 0.01?

F = 8.10

The following data represent the means for each treatment condition in a two-factor experiment. Note that one mean is not given. Which value for the missing mean would result in no main effect for factor B?

M = 50

For a two-factor experiment with 2 levels of factor A and 3 levels of factor B and n = 10 subjects in each treatment condition, how many participants are in each level of factor A?

n = 30

A two-factor research study is used to evaluate the effectiveness of a new blood-pressure medication. In this two-factor study, factor A is medication versus no medication and factor B is male versus female. The medicine is expected to reduce blood pressure for both males and females, but it is expected to have a much greater effect for males. Which pattern of results should be obtained if the medication works as predicted?

a significant main effect for factor A and a significant interaction