Question 1

Using an independent-measures t,the 90% confidence interval for the difference between two population means ranges from 19 to 23.Based on this confidence interval,how big is the difference between the two sample means?

Accepted Answer

A) 4 points 
B) 19 points 
C) 21 points 
D) 23 points

Question 2

If one sample has n = 4 and SS = 90 and a second sample has n = 8 and SS = 150,then the estimated standard error for the sample mean difference is 9 points.

Accepted Answer

A) True 
 B)False

Question 3

An independent-measures research study uses two samples,each with n = 15 participants.If the data produce a t statistic of t = 2.760,which of the following is the correct decision for a two-tailed hypothesis test?

Accepted Answer

A) Reject the null hypothesis with α = .05 but fail to reject with α = .01 
B) Reject the null hypothesis with either α = .05 or α = .01 
C) Fail to reject the null hypothesis with either α = .05 or α = .01 
D) Cannot answer without additional information

Question 4

A researcher reports t(22)= 5.30,p < .01 for an independent-measures experiment.How many individuals participated in the entire experiment?

Accepted Answer

A) 20 
B) 21 
C) 23 
D) 24

Question 5

Two samples,each with n = 8,produce an independent-measures t statistic of t = -2.15.Which of the following decisions is justified for a two-tailed test?

Accepted Answer

A) Reject H0 with α = .05 but fail to reject with α = .01 
B) Reject H0 with both α = .05 and α = .01 
C) Fail to reject H0 with both α = .05 and α = .01 
D) Fail to reject H0 with α = .05 but reject H0 with α = .01

Question 6

For an independent-measures study,the width of a confidence interval estimating µ₁ - µ₂ depends on the size of the difference between M₁ and M₂.

Accepted Answer

A) True 
 B)False

Question 7

If two sample variances are not equal,the pooled variance will be closer to the larger of the two variances.

Accepted Answer

A) True 
 B)False

Question 8

For an independent-measures t statistic,the estimated standard error measures how much difference is reasonable to expect between the sample means for two samples selected from the same population.

Accepted Answer

A) True 
 B)False

Question 9

Two samples,each with n = 9 scores,produce an independent-measures t statistic of t = 2.00.If the effect size is measured using r²,what is the value of r²?

Accepted Answer

A) 4/16 
B) 4/20 
C) 2/16 
D) 2/18

Question 10

One sample of n = 8 scores has a variance of s² = 6 and a second sample of n = 8 scores has a variance of s² = 10.If the pooled variance is computed for these two samples,then the value obtained will be ______.

Accepted Answer

A) closer to 6 than to 10 
B) closer to 10 than to 6 
C) exactly halfway between 6 and 10 
D) cannot be determined without more information

Question 11

A researcher predicts that scores in treatment A will be higher than scores in treatment B.If the mean for the 10 participants in treatment A is 4 points higher than the mean for the 10 participants in treatment B and the data produce t = 2.095,what decision should be made?

Accepted Answer

A) With α = .05, reject H0 for both a one-tailed and a two-tailed test 
B) With α = .05, fail to reject H0 for both a one-tailed and a two-tailed test 
C) With α = .05, reject H0 for a one-tailed test but fail to reject for a two-tailed test 
D) With α = .05, reject H0 for a two-tailed test but fail to reject for a one-tailed test

Question 12

An independent-measures research study uses two samples,each with n = 10 participants.If the data produce a t statistic of t = 2.095,which of the following is the correct decision for a two-tailed hypothesis test?

Accepted Answer

A) Reject the null hypothesis with α = .05 but fail to reject with α = .01 
B) Reject the null hypothesis with either α = .05 or α = .01 
C) Fail to reject the null hypothesis with either α = .05 or α = .01 
D) Cannot answer without additional information

Question 13

For an independent-measures t statistic,you typically must compute the pooled variance before calculating the estimated standard error.

Accepted Answer

A) True 
 B)False

Question 14

The data from an independent-measures research study produce a sample mean difference of 6 points and an estimated standard error of 2 points.If there are n = 8 scores in each sample,what is the value for the t statistic?

Accepted Answer

A) 6/2 
B) 6/4 
C) 6/0.25 
D) 6/0.50

Question 15

One sample has n = 10 scores and a variance of s² = 20,and a second sample has n = 15 scores and a variance of s² = 30.What can you conclude about the pooled variance for these two samples?

Accepted Answer

A) It will be closer to 20 than to 30. 
B) It will be closer to 30 than to 20. 
C) It will be exactly halfway between 20 and 30. 
D) Cannot be determined without more information.

Question 16

If two separate samples have M₁ = 10 and M₂ = 18 with a pooled variance of 16,then Cohen's d = 0.50.

Accepted Answer

A) True 
 B)False

Question 17

One sample has M = 18 and a second sample has M = 14.If the pooled variance for the two samples is 16,what is the value of Cohen's d?

Accepted Answer

A) 0.25 
B) 0.50 
C) 1.00 
D) Cannot be determined with the information given

Question 18

One sample has a variance of s² = 10 and a second sample has a variance of s² = 6.Which of the following most accurately describes the pooled variance for the two samples?

Accepted Answer

A) Closer to 6 than to 10 
B) Closer to 10 than to 6 
C) Somewhere between 6 and 10 
D) Around 16

Question 19

Which of the following research situations would be most likely to use an independent-measures design?

Accepted Answer

A) Examine the development of vocabulary as a group of children mature from age 2 to age 3. 
B) Examine the long-term effectiveness of a stop-smoking treatment by interviewing subjects 2 months and 6 months after the treatment ends. 
C) Compare the mathematics skills for 9th-grade boys versus 9th-grade girls. 
D) Compare the blood-pressure readings before medication and after medication for a group a patients with high blood pressure.

Question 20

What is assumed by the homogeneity of variance assumption?

Accepted Answer

A) The two samples have equal variances. 
B) The two sample variances are not equal. 
C) The two populations have equal variances. 
D) The two population variances are not equal.

Exam 10: The t Test for Two Independent Samples

Using an independent-measures t,the 90% confidence interval for the difference between two population means ranges from 19 to 23.Based on this confidence interval,how big is the difference between the two sample means?

If one sample has n = 4 and SS = 90 and a second sample has n = 8 and SS = 150,then the estimated standard error for the sample mean difference is 9 points.

An independent-measures research study uses two samples,each with n = 15 participants.If the data produce a t statistic of t = 2.760,which of the following is the correct decision for a two-tailed hypothesis test?

A researcher reports t(22) = 5.30,p < .01 for an independent-measures experiment.How many individuals participated in the entire experiment?

Two samples,each with n = 8,produce an independent-measures t statistic of t = -2.15.Which of the following decisions is justified for a two-tailed test?

For an independent-measures study,the width of a confidence interval estimating µ₁ - µ₂ depends on the size of the difference between M₁ and M₂.

If two sample variances are not equal,the pooled variance will be closer to the larger of the two variances.

For an independent-measures t statistic,the estimated standard error measures how much difference is reasonable to expect between the sample means for two samples selected from the same population.

Two samples,each with n = 9 scores,produce an independent-measures t statistic of t = 2.00.If the effect size is measured using r²,what is the value of r²?

One sample of n = 8 scores has a variance of s² = 6 and a second sample of n = 8 scores has a variance of s² = 10.If the pooled variance is computed for these two samples,then the value obtained will be ______.

A researcher predicts that scores in treatment A will be higher than scores in treatment B.If the mean for the 10 participants in treatment A is 4 points higher than the mean for the 10 participants in treatment B and the data produce t = 2.095,what decision should be made?

An independent-measures research study uses two samples,each with n = 10 participants.If the data produce a t statistic of t = 2.095,which of the following is the correct decision for a two-tailed hypothesis test?

For an independent-measures t statistic,you typically must compute the pooled variance before calculating the estimated standard error.

The data from an independent-measures research study produce a sample mean difference of 6 points and an estimated standard error of 2 points.If there are n = 8 scores in each sample,what is the value for the t statistic?

One sample has n = 10 scores and a variance of s² = 20,and a second sample has n = 15 scores and a variance of s² = 30.What can you conclude about the pooled variance for these two samples?

If two separate samples have M₁ = 10 and M₂ = 18 with a pooled variance of 16,then Cohen's d = 0.50.

One sample has M = 18 and a second sample has M = 14.If the pooled variance for the two samples is 16,what is the value of Cohen's d?

One sample has a variance of s² = 10 and a second sample has a variance of s² = 6.Which of the following most accurately describes the pooled variance for the two samples?

Which of the following research situations would be most likely to use an independent-measures design?

What is assumed by the homogeneity of variance assumption?