A sample of n = 4 scores has ss = 60. what is the variance for this sample?

1. This is an OPEN BOOK/OPEN NOTE exam

CHAPTER 9

Which of the following is a fundamental difference between the t statistic and a z-score?
(Points : 2)
The t statistic uses the sample mean in place of the population mean.

The t statistic uses the sample variance in place of the population variance

The t statistic computes the standard error by dividing the standard deviation by n - 1 instead of dividing by n.
All of these are differences between t and z.

Question 2. 2. A sample of n=4 scores has SS=60. What is the variance for this sample? (Points : 2)
15
16
20
30

Question 3. 3. A sample of n = 25 scores has a mean of M = 40 and a standard deviation of s = 10. What is the estimated standard error for the sample mean?
(Points : 2)
4
2
.4
1

Question 4. 4. A researcher conducts a hypothesis test using a sample from an unknown population. If the t statistic has df = 30, how many individuals were in the sample?
(Points : 2)
n=29
n=30
n=31
Cannot be determined from the information given.

Question 5. 5. 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?
(Points : 2)
d=0.125
d=0.25
d=0.50
Cohen's d cannot be determined without knowing the sample size.

Question 6. 6. With α = .05, what is the critical t value for a one-tailed test with n = 15?
(Points : 2)
t = 1.761

t = 1.753

t = 2.145

t = 2.131

Question 7. 7. A hypothesis test with a sample of n = 25 participants produces a t statistic of t = +2.53. Assuming a one-tailed test with the critical region in the right-hand tail, what is the correct decision? (Points : 2)
The researcher can reject the null hypothesis with α = .05 but not with α = .01.

The researcher can reject the null hypothesis with either α = .05 or α = .01.

The researcher must fail to reject the null hypothesis with either α = .05 or α = .01.
It is impossible to make a decision about H0 without more information.

Question 8. 8. A sample has a mean of M = 39.5 and a standard deviation of s = 4.3, and produces a t statistic of t = 2.14. For a two-tailed hypothesis test with α = .05, what is the correct statistical decision for this sample?
(Points : 2)
The researcher can reject the null hypothesis with α = .05 but not with α = .01

The researcher can reject the null hypothesis with either α = .05 or α = .01

The researcher must fail to reject the null hypothesis with either α = .05 or α = .01.

It is impossible to make a decision about H0 without more information.

Question 9. 9. CHAPTER 10

If an independent-measures design is being used to compare two treatment conditions, then how many different groups of participants would be needed and how many scores would there be for each participant?

(Points : 2)
1 group, 1 score each
2 groups, 1 score each
1 group, 2 scores each

2 groups, 2 scores each

Question 10. 10. An independent-measures study uses n = 15 participants in each group to compare two treatment conditions. What is the df value for the t statistic for this study?
(Points : 2)
14
15
28
29

Question 11. 11. What is the pooled variance for the following two samples?

Sample 1: n = 8 and SS = 168
Sample 2: n = 6 and SS = 120

(Points : 2)
7
7

20.57
24

Question 12. 12. Two samples, each with n = 5 scores, have a pooled variance of 40. What is the estimated standard error for the sample mean difference?
(Points : 2)
4
8
10
20

Question 13. 13. An independent-measures study with n = 6 in each sample produces a sample mean difference of 4 points and a pooled variance of 12. What is the value for the t statistic?
(Points : 2)
1
2
4/2

4/8

Question 14. 14. 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?
(Points : 2)
Reject the null hypothesis with α = .05 but fail to reject with α = .01

Reject the null hypothesis with either α = .05 or α = .01

Fail to reject the null hypothesis with either α = .05 or α = .01

Cannot answer without additional information

Question 15. 15. 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?
(Points : 2)
4/16

4/20

2/16

2/18

Question 16. 16. Chapter 11

A repeated-measures study uses a total of n = 10 participants to compare two treatment conditions. How many scores are measured in this study, and how many scores are actually used to compute the sample mean and the sample variance?
(Points : 2)
20 measured and 10 used
20 measured and 20 used
10 measured and 10 used
10 measured and 20 used

Question 17. 17. The following data were obtained from a repeated-measures research study. What is the value of MD for these data?

Subject 1st 2nd
#1 10 15
#2 4 8
#3 7 5
#4 6 11

(Points : 2)
3
3.5
4
4.5

Question 18. 18. For a repeated-measures study comparing two treatment conditions, a researcher obtains a sample of n = 9 difference scores with a mean of MD = 4 and a variance of s2 = 36. What is the value for the repeated-measures t statistic for these data?
(Points : 2)
4/2
4/4
4/6
4/36

Question 19. 19. A research report describing the results from a repeated-measures t test states that “t(22) = 1.71, p > .05.” From this report, what was the outcome of the hypothesis test?
(Points : 2)
Reject the null hypothesis with a sample of n = 23 participants

Fail to reject the null hypothesis with a sample of n = 23 participants

Reject the null hypothesis with a sample of n = 22 participants

Fail to reject the null hypothesis with a sample of n = 22 participants

Question 20. 20. A researcher conducts a repeated-measures study to evaluate a treatment with a sample of n = 16 participants and obtains a t statistic of t = 1.94. The treatment is expected to increase scores and the sample mean shows an increase. Which of the following is the correct decision for a hypothesis test using α = .05.
(Points : 2)
Reject the null hypothesis with a one-tailed test but fail to reject with two tails

Reject the null hypothesis with either a one-tailed or a two-tailed test

Fail to reject the null hypothesis with either a one-tailed or a two-tailed test

Fail to reject the null hypothesis with a one-tailed test but reject with two tails

Question 21. 21. Compared to an independent-measures design, a repeated-measured study is more likely to find a significant effect because it reduces the contribution of variance due to ______. (Points : 2)
time-related factors

order effects

the effect of the treatment
individual differences

Question 22. 22. A sample of n = 9 college students is used to evaluate the effectiveness of a new Study Skills Workshop. Each student’s grade point average (GPA) is recorded for the semester before the workshop and for the semester after the workshop. The average GPA improved by MD = 0.60 points with s2 = 0.09. The researcher would like to use the sample to estimate how much effect the workshop would have for the entire college population. Which of the following is the 80% confidence interval for these data? (Points : 2)
µD = 0.60 + 0.01(1.397)

µD = 0.60 + 0.09(1.860)

µD = 0.60 + 0.10(1.397)
µD = 0.60 + 0.10(1.860)

Question 23. 23. CHAPTER 12
On average, what value is expected for the F-ratio if the null hypothesis is true?
(Points : 2)
0
1.00
k-1
N-k

Question 24. 24. 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 X2 = 94. For this study, what is SSwithin?
(Points : 2)
10
24
34
68

Question 25. 25. In analysis of variance, what is measured by the MS values?
(Points : 2)
Sample variances
Population variance
The average distance from one mean to another.
The total variability for the set of N scores.

Question 26. 26. For an independent-measures ANOVA comparing three treatments with a sample of n = 5 in each treatment, what is the critical value for the F-ratio using α = .05? (Points : 2)
3.88
3.49
3.74
3.34

Question 27. 27. A researcher reports an F-ratio with df = 2, 18 from an independent-measures research study. Based on the df values, how many treatments were compared in the study, and what was the total number of subjects participating in the study?
(Points : 2)
2 treatments and 19 subjects
2 treatments and 20 subjects
3 treatments and 21 subjects
3 treatments and 22 subjects

Question 28. 28. An analysis of variance is used to evaluate the mean differences for a research study comparing four treatments with a separate sample of n = 8 in each treatment. If the data produce an F-ratio of F = 4.60, which of the following is the correct statistical decision? (Points : 2)
Reject the null hypothesis with α = .05 but not with α = .01
Reject the null hypothesis with either α = .05 or α = .01
Fail to reject the null hypothesis with either α = .05 or α = .01

There is not enough information to make a statistical decision

Question 29. 29. What is the purpose for post tests? (Points : 2)
To determine whether or not a Type I error was committed

To determine how much difference exists between the treatments

To determine which treatments are significantly different

None of these

Question 30. 30. CHAPTER 13
In an independent-measures ANOVA, individual differences contribute to the variance in the numerator and in the denominator of the F-ratio. For a repeated-measures ANOVA, what happens to the individual differences in the denominator of the F-ratio?
(Points : 2)
They do not exist because the same individuals participate in all of the treatments.

They are measured and subtracted out in the second stage of the analysis.

Individual differences contribute to the variance in the denominator.

None of the other options accurately describes individual differences in the denominator.