Question 1

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?

Accepted Answer

A)  Researcher A.
B)  Researcher B.
C)  The likelihood is the same for both researchers.
D)  There is not enough information to answer this question. A

Question 2

Which of the following summarizes a t test that was significant and associated with a large effect size?

Accepted Answer

A)  t(22) = 3.02,p 
B)  t(30) = 1.03,p > .05,d = .20
C)  t(60) = 1.76,p > .05,d = .45
D)  t(12) = 2.95,p < .05,d = .82 D

Question 3

Two researchers (A andB)compute a one-sample t test.For both tests,the mean difference between the sample and value stated in the null hypothesis is 5,but the standard error is smaller for Researcher A.Which test is more likely to result in a decision to reject the null hypothesis?

Accepted Answer

A)  Researcher A.
B)  Researcher B.
C)  The likelihood is the same for both researchers.
D)  There is not enough information to answer this question. A

Question 4

A researcher measures mean health scores of children at a local school and compares these scores to the mean health score known in the general population.Assuming that the population variance is unknown,what type of t test is appropriate for this study?

Accepted Answer

A)  one-sample t test
B)  two-independent sample t test
C)  There is not enough information to answer this question.

Question 5

A researcher has participants rate the likability of a sexually promiscuous person described in a vignette as being male (n = 20)or female (n = 12).The mean likability ratings in each group were 4.0.If the null hypothesis is that there is no difference in likability ratings,then do likability ratings differ at a .05 level of significance?

Accepted Answer

A)  Yes,this result is significant,p 
B)  No,this result is not significant,t(30) = 0.
C)  No,this result is not significant,t(30) = 1.00.
D)  There is not enough information to answer this question,because the variance in each sample is not given.

Question 6

A local elementary school determined that the average number of volunteers for their "Step into Spring" annual fundraiser has been 14 persons on average (per event).After taking additional measures to recruit volunteers this year,they got 28 people to volunteer.Test whether these additional measures increased the number of volunteers at a .05 level of significance.

Accepted Answer

A)  Yes,because the number of volunteers doubled;this is a significant increase.
B)  No,this is not a significant increase because the error term is too large.
C)  This would have been significant if it were a two-tailed test.
D)  There is not enough information to answer this question.

Question 7

The ________ is an inferential statistic used to determine the number of standard deviations in a t distribution that a sample mean deviates from the mean value or mean difference stated in the null hypothesis.

Accepted Answer

A)  t distribution
B)  t statistic
C)  standard error
D)  degrees of freedom

Question 8

If d = 0.28,then we conclude that mean scores in some population have shifted 0.28 standard deviations below the mean.

Accepted Answer

A) True 
 B)False

Question 9

A researcher conducts a study and concludes that a new behavioral health treatment program significantly reduces one's risk for disease compared with risk levels in the general population (d = -0.64).Interpret the size of this effect.

Accepted Answer

A)  64% of the variability in risk level can be accounted for by the new treatment.
B)  64% of the new treatment can be accounted for by the risk levels.
C)  Risk levels in the population shifted 0.64 standard deviations below the mean.
D)  Risk levels in the population shifted 0.64 standard deviations above the mean.

Question 10

The p value is reported with the test statistic of a one-sample and a two-independent sample t test using APA format.

Accepted Answer

A) True 
 B)False

Question 11

It is most appropriate to report effect size with a significant result.Why is it generally inappropriate to report effect size with insignificant results?

Accepted Answer

A)  Because insignificant results will always have an effect size equal to 0.
B)  Because insignificant results indicate that an effect size is also insignificant.
C)  Because it makes little sense to report the size of an effect that you just concluded doesn't exist.
D)  Because the probability of the size of an effect varies depending on the significance of the result.

Question 12

A t test is associated with n - 1 degrees of freedom.

Accepted Answer

A) True 
 B)False

Question 13

A researcher finds that the mean difference in productivity between employees working the morning shift (n = 16)and the night shift (n = 10)is 5.0 units,and the estimated standard error for the difference is 2.7 units.If the null hypothesis states that there is no difference in productivity,then is this result significant at a .05 level of significance?

Accepted Answer

A)  Yes,this result is significant.
B)  No,this result is not significant.
C)  There is not enough information to answer this question.

Question 14

The critical values are reported with the test statistic of a one-sample and a two-independent sample t test using APA format.

Accepted Answer

A) True 
 B)False

Question 15

A researcher reports the following result for a lower-tail critical test at a .05 level of significance,t(40)= 3.212,and accurately concludes that this result is significant.

Accepted Answer

A) True 
 B)False

Question 16

The estimated standard error in the t statistic uses the ________ to estimate the ________ when the population variance is unknown.

Accepted Answer

A)  sample variance;population variance
B)  population variance;sample variance
C)  standard error;sample variance
D)  degrees of freedom;sample size

Question 17

As a requirement for the t test,researchers compute any type of t test with samples selected from populations in which

Accepted Answer

A)  the population variance is known
B)  the population size is very large
C)  the population variance is unknown
D)  the population is the same size as the sample

Question 18

A researcher conducts two t tests.Test 1 is a one-tailed test with a smaller sample size at a .05 level of significance.Test 2 is a one-tailed test with a larger sample size at a .05 level of significance.What do you know about the critical values for each test?

Accepted Answer

A)  Test 1 is associated with smaller critical values.
B)  Test 2 is associated with smaller critical values.
C)  Each test is associated with the same critical values.
D)  It depends;there is not enough information to answer this question.

Question 19

A researcher reports that stress levels among nurses are higher compared to stress levels in the general population,t(20)= 2.086,p = .05 (d = .12).Was this a one-tailed or a two-tailed test?

Accepted Answer

A)  One-tailed test because the p value is equal to .05
B)  Two-tailed test because the p value is equal to .05
C)  It could be a one- or a two-tailed test

Question 20

Computing a two-independent sample t test is appropriate when

Accepted Answer

A)  different participants are assigned to each group
B)  the population variance is unknown
C)  participants are observed one time
D)  all of the above

Exam 9: Testing Means: One-Sample and Two-Independent Sample T Tests

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?

Which of the following summarizes a t test that was significant and associated with a large effect size?

Two researchers (A andB) compute a one-sample t test.For both tests,the mean difference between the sample and value stated in the null hypothesis is 5,but the standard error is smaller for Researcher A.Which test is more likely to result in a decision to reject the null hypothesis?

A researcher measures mean health scores of children at a local school and compares these scores to the mean health score known in the general population.Assuming that the population variance is unknown,what type of t test is appropriate for this study?

The ________ is an inferential statistic used to determine the number of standard deviations in a t distribution that a sample mean deviates from the mean value or mean difference stated in the null hypothesis.

If d = 0.28,then we conclude that mean scores in some population have shifted 0.28 standard deviations below the mean.

A researcher conducts a study and concludes that a new behavioral health treatment program significantly reduces one's risk for disease compared with risk levels in the general population (d = -0.64) .Interpret the size of this effect.

The p value is reported with the test statistic of a one-sample and a two-independent sample t test using APA format.

It is most appropriate to report effect size with a significant result.Why is it generally inappropriate to report effect size with insignificant results?

A t test is associated with n - 1 degrees of freedom.

The critical values are reported with the test statistic of a one-sample and a two-independent sample t test using APA format.

A researcher reports the following result for a lower-tail critical test at a .05 level of significance,t(40)= 3.212,and accurately concludes that this result is significant.

The estimated standard error in the t statistic uses the to estimate the when the population variance is unknown.

As a requirement for the t test,researchers compute any type of t test with samples selected from populations in which

A researcher conducts two t tests.Test 1 is a one-tailed test with a smaller sample size at a .05 level of significance.Test 2 is a one-tailed test with a larger sample size at a .05 level of significance.What do you know about the critical values for each test?

A researcher reports that stress levels among nurses are higher compared to stress levels in the general population,t(20) = 2.086,p = .05 (d = .12) .Was this a one-tailed or a two-tailed test?

Computing a two-independent sample t test is appropriate when