__________ 19. The following question(s) require(s) the use of Tables 10–8 and 1

Question

__________ 19. The following question(s) require(s) the use of Tables 10–8 and 10–9 from your text.

Suppose you are planning a study involving five groups and you expect a medium effect size (and will use the .05 level). For 80% power, how many participants will you need in each group?
a. 240
b. 52
c. 16
d. 39

21. Match the term on the left with its correct definition on the right:
__________ a. analysis of variance hypothesis-testing procedure for studies with three or more groups
__________ b. F ratio in ANOVA, ratio of the between-groups population variance estimate to the within-groups estimate
__________ c. grand mean in ANOVA, overall average of all the scores, regardless of what group they are in (and when group sizes are equal, it is the mean of the group means)
__________ d. F table display of cutoff scores on the F distribution for various degrees of freedom and significance levels
__________ e. between-groups degrees of freedom in a given study, the number of groups minus 1; also called the numerator degrees of freedom
__________ f. protected t tests in ANOVA, t tests among pairs of means after finding that the F for the overall difference among the means is significant

__________ 22. Suppose you were conducting an ANOVA with four groups of five participants each. What are your within-groups and between-groups degrees of freedom, respectively?
a. 16; 4
b. 12; 3
c. 20; 3
d. 16; 3


__________ 23. Suppose you wish to compare three medical treatments for bipolar disorder (Treatments A, B, and C). The null hypothesis would be that:
a. the several populations being compared all have different means
b. the several populations being compared all have the same mean
c. the true population variances differ by a factor of 10
d. the true population variances differ by a factor of sample size


__________ 24. In an analysis of variance, the between-group estimate of the population variance is 30 and the within-group estimate is 25. What is the F ratio?
a. 25/(30-25) = 5.00
b. (30-25)/30 = 0.17
c. 25/30 = .83
d. 30/25 = 1.20


__________ 25. In ANOVA, the ratio of the between-groups population variance estimate to the within-groups population variance estimate is known as the:
a. F ratio
b. T ratio
c. ANOVA ratio
d. distribution


__________ 26. If three samples have means of 10, 20, and 15, respectively, what is their grand mean?
a. 5
b. 10
c. 15
d. 20


27. For the following question(s): Suppose a researcher wants to study the effectiveness of a new reading program for students who have not acquired the necessary reading skills by the time they reach the eighth grade. A randomly selected group of 50 students from a local junior high with poor reading skills will undergo the new reading program. Another group of 50 randomly selected students with poor reading skills will undergo regular reading classes. A month later, the reading skills of all 100 students are assessed to determine whether the program was successful.

In a t test for independent means, the difference between the means of your two samples is divided by the standard deviation of the __________ to get the t score.

__________ 28. An analysis of variance (ANOVA) differs from a test for independent means (t test) in that an ANOVA:
a. is usually used to compare the means of two groups but a t test is used to compare three groups
b. is used to compare the means of three or more groups whereas a t test is used to compare two groups
c. is conducted before the experiment whereas a t test is conducted after the experiment
d. figures variances as part of the analysis whereas a t test does not figure variances

Explanation / Answer

I have answered some problems are as follows

22) The between-groups df
is the number of groups -1 = 4 -1
= 3.

The within-groups df is
The number of groups times (number of observations in each group -1)
= 4 times (5-1) = 4(4)=16

Ans D, (df within = N-K dfbetween= Ngroup-1)

Ans d
--------------------------------------------------------
23) The several populations being compared all have the same mean
i.e 1=2=3

Ans b

_____________________________________________________________

24 )The estimate of the population variance is 30

and the within-group estimate is 25.

The estimate of the population variance is 30/ the within-group estimate is 25.

30/25=1.20

Ans d

______________________________________________

25)  F ratio

____________________________________________________

26) C

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