Question 1

The results from an independent-measures t hypothesis test are reported as "t(14) = 2.13,
p > .05, two tailed." For this test, the null hypothesis was rejected.

Accepted Answer

A) True 
 B)False

Question 2

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 3

One sample has n = 7 scores with SS = 40, and a second sample has n = 5 scores with SS = 80.The pooled variance for these two samples is 120/10 = 12.

Accepted Answer

A) True 
 B)False

Question 4

The data from an independent-measures research study produce a sample mean difference of 4 points and a pooled variance of 16.If there are n = 8 scores in each sample, then what is the estimated standard error for the sample mean difference?

Accepted Answer

A) 2 
B) 4 
C) 16 
D) 128

Question 5

If the df value for an independent-measures t statistic is an odd number, then it is impossible for the two samples to be the same size.

Accepted Answer

A) True 
 B)False

Question 6

One sample of n = 8 scores has a variance of s2 = 6 and a second sample of n = 8 scores has 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 half way between 6 and 10 
D) cannot be determined without more information

Question 7

Which of the following confidence intervals also indicates a significant difference between treatments with α = .05?

Accepted Answer

A) Estimate that μ1 - μ2 is in an interval between 2 and 10 with 90% confidence. 
B) Estimate that μ1 - μ2 is in an interval between -2 and 8 with 90% confidence. 
C) Estimate that μ1 - μ2 is in an interval between 2 and 10 with 95% confidence. 
D) Estimate that μ1 - μ2 is in an interval between -2 and 8 with 95% confidence.

Question 8

Which of the following accurately describes an independent-measures study?

Accepted Answer

A) It uses a different group of participants for each of the treatment conditions being compared. 
B) It uses the same group of participants in all of the treatment conditions being compared. 
C) It uses one group of participants to evaluate a hypothesis about one population mean. 
D) none of the other alternatives is correct

Question 9

If the two samples are the same size, the independent measures t statistic will have an even number for degrees of freedom.

Accepted Answer

A) True 
 B)False

Question 10

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

Accepted Answer

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

Question 11

An independent-measures research study uses a total of 18 participants to compare two treatment conditions.If the results are used to construct a 90% confidence interval for the population mean difference, then the t values will be ±1.746.

Accepted Answer

A) True 
 B)False

Question 12

The results of an independent-measures research study are reported as "t(20) = 2.12, p < .05, two tails." For this study, what t values formed the boundaries for the critical region?

Accepted Answer

A) ±2.093 
B) ±2.086 
C) ±2.080 
D) ±2.074

Question 13

Two separate samples, each with n = 10 scores, will produce an independent-measures t statistic with df = 19.

Accepted Answer

A) True 
 B)False

Question 14

An independent-measures study comparing two treatment conditions produces a t statistic with df = 18.If the two samples are the same size, how many participants were in each of the samples?

Accepted Answer

A) 9 
B) 10 
C) 19 
D) 20

Question 15

Which of the following is the correct null hypothesis for an independent-measures t test?

Accepted Answer

A) μ1 - μ2 = 0 
B) M1 - M2 = 0 
C) μ1 - μ2 EQ \O(=,/) 0 
D) M1 - M2 EQ \O(=,/) 0

Question 16

If other factors are held constant, which of the following sets of data would produce the largest value for an independent-measures t statistic?

Accepted Answer

A) The two samples both have n = 15 with sample variances of 20 and 25. 
B) The two samples both have n = 15 with variances of 120 and 125. 
C) The two samples both have n = 30 with sample variances of 20 and 25. 
D) The two samples both have n = 30 with variances of 120 and 125.

Question 17

An independent-measures study has M1 = 49 and M2 = 45 with an estimated standard error of 4.For this study, Cohen's d = 4/4 = 1.00.

Accepted Answer

A) True 
 B)False

Question 18

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 half way between 20 and 30. 
D) Cannot be determined without more information.

Question 19

Two separate samples are being used to estimate the population mean difference between two treatment conditions.Which of the following would produce the widest confidence interval?

Accepted Answer

A) n1 = n2 = 10 with a pooled variance of 10 
B) n1 = n2 = 10 with a pooled variance of 100 
C) n1 = n2 = 20 with a pooled variance of 10 
D) n1 = n2 = 20 with a pooled variance of 100

Question 20

In an independent-measures hypothesis test, what must be true if t = 0?

Accepted Answer

A) The two population means must be equal. 
B) The two sample means must be equal. 
C) The two sample variances must be equal. 
D) None of the other 3 choices is correct.

Exam 10: The T Test for Two Independent Samples

The results from an independent-measures t hypothesis test are reported as "t(14) = 2.13, p > .05, two tailed." For this test, the null hypothesis was rejected.

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 n = 7 scores with SS = 40, and a second sample has n = 5 scores with SS = 80.The pooled variance for these two samples is 120/10 = 12.

The data from an independent-measures research study produce a sample mean difference of 4 points and a pooled variance of 16.If there are n = 8 scores in each sample, then what is the estimated standard error for the sample mean difference?

If the df value for an independent-measures t statistic is an odd number, then it is impossible for the two samples to be the same size.

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

Which of the following confidence intervals also indicates a significant difference between treatments with α = .05?

Which of the following accurately describes an independent-measures study?

If the two samples are the same size, the independent measures t statistic will have an even number for degrees of freedom.

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

An independent-measures research study uses a total of 18 participants to compare two treatment conditions.If the results are used to construct a 90% confidence interval for the population mean difference, then the t values will be ±1.746.

The results of an independent-measures research study are reported as "t(20) = 2.12, p < .05, two tails." For this study, what t values formed the boundaries for the critical region?

Two separate samples, each with n = 10 scores, will produce an independent-measures t statistic with df = 19.

An independent-measures study comparing two treatment conditions produces a t statistic with df = 18.If the two samples are the same size, how many participants were in each of the samples?

Which of the following is the correct null hypothesis for an independent-measures t test?

If other factors are held constant, which of the following sets of data would produce the largest value for an independent-measures t statistic?

An independent-measures study has M₁ = 49 and M₂ = 45 with an estimated standard error of 4.For this study, Cohen's d = 4/4 = 1.00.

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?

Two separate samples are being used to estimate the population mean difference between two treatment conditions.Which of the following would produce the widest confidence interval?

In an independent-measures hypothesis test, what must be true if t = 0?