21 When comparing more than two treatment means why should y

21. When comparing more than two treatment means, why should you use an analysis of variance instead of using several t tests?

a.

Using several t tests increases the risk of a Type I error.

b.

Using several t tests increases the risk of a Type II error.

c.

The analysis of variance is more likely to detect a treatment effect.

d.

There is no advantage to using an analysis of variance instead of several t tests.

22. On average, what value is expected for the F-ratio if the null hypothesis is true?

a.

0

b.

1.00

c.

k – 1

d.

N – k

23. 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 SS_within?

a.

10

b.

24

c.

34

d.

68

24. An analysis of variances produces df_total = 29 and df_within = 27. For this analysis, what is df_between?

a.

1

b.

2

c.

3

d.

Cannot be determined without additional information

25. Which of the following is expected if the null hypothesis is true for an analysis of variance?

a.

SS_between should be about the same size as SS_total

b.

SS_between should be about the same size as SS_within

c.

MS_between should be about the same size as MS_total

d.

MS_between should be about the same size as MS_within

26. The following table shows the results of an analysis of variance comparing three treatment conditions with a sample of n = 10 participants in each treatment. Note that several values are missing in the table. What is the missing value for SS_total?

a.

22

b.

30

c.

54

d.

74

Source:   SS df MS

Between: 20 xx xx F=5.00

Within: xx xx xx

Total: xx xx

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?

a.

2 treatments and 19 subjects

b.

2 treatments and 20 subjects

c.

3 treatments and 21 subjects

d.

3 treatments and 22 subjects

28. In an analysis of variance, which of the following is determined by the size of the sample mean differences?

a.

SS_between

b.

SS_within

c.

df_between

d.

df_within

29. A research report concludes that there are significant differences among treatments, with “F(2, 24) = 8.62, p < .01.” If the same number of participants was used in all of the treatment conditions, then how many individuals were in each treatment?

a.

7

b.

9

c.

10

d.

30

30. What is the purpose for post tests?

a.

To determine whether or not a Type I error was committed

b.

To determine how much difference exists between the treatments

c.

To determine which treatments are significantly different

d.

None of these

a.	Using several t tests increases the risk of a Type I error.
b.	Using several t tests increases the risk of a Type II error.
c.	The analysis of variance is more likely to detect a treatment effect.
d.	There is no advantage to using an analysis of variance instead of several t tests.

Solution

21

The probability of making a Type I error increases as the number of tests increase.

so I will say literal a is the answer

Using several t tests increases the risk of a Type I error.

22)

You can see this question in this way
When the treatment effect is zero (H0 is true), the error term measure the same sources of variances as the numerator of the F-ratio, so the value of the F-ratio is expected to be nearly equal to 1

24)

29-27 = 2

25)

MSbetween should be about the same size as MSwithin

27)

3 treatments and 21 subjects

df=2------------2+1=3

18+3=21