11.13 Write an appropriate statistical model for Exercise 11.1.
11.14 Write an appropriate statistical model for Exercise 11.2.
11.15 Write an appropriate statistical model for Exercise 11.3. Save it for later use in Chapter 13.
11.16 When Fis less than 1, we usually write “,1” rather than the actual value. What meaning
can be attached to an Fappreciably less than 1? Can we speak intelligently about an F
“significantly” less than 1? Include E(MS) in your answer.
11.17 Howell and Huessy (1981) classified children as exhibiting (or not exhibiting) attention
deficit disorder (ADD)-related behaviors in second, fourth, and fifth grade. The subjects
were then sorted on the basis of the year(s) in which the individual was classed as exhibit-
ing such behavior. They then looked at GPA for these children when the latter were in high
school. The data are given in terms of mean GPA per group.
Exercises 359Never Second Fourth Second
ADD Only Only and Fourth
Mean 2.6774 1.6123 1.9975 2.0287
S.D. 0.9721 1.0097 0.7642 0.5461
n 201 13 12 8
Second,
Fifth Second Fourth Fourth,
Only and Fifth and Fifth and Fifth
Mean 1.7000 1.9000 1.8986 1.4225
S.D. 0.8788 1.0318 0.3045 0.5884
n 14 9 7 8
Run the analysis of variance and draw the appropriate conclusion.11.18 Rerun the analysis of Exercise 11.17, leaving out the Never ADD group. In what way does
this analysis clarify the interpretation of the data?
11.19 Apply a square-root transformation to the data in Table 11.5.
11.20 Run the analysis of variance for the transformed data you obtained in Exercise 11.19.
11.21 Calculate and for the data in Exercise 11.17.
11.22 Darley and Latané (1968) recorded the speed with which subjects summoned help for a per-
son in trouble. Subjects thought either that they were the only one listening to the person
(Group 1, n 5 13), that one other person was listening (Group 2, n 5 26), or that four other
people were listening (Group 3, n 5 13). The dependent variable was the speed with which
the person summoned help ( 5 1/time 3 100). The mean speed scores for the three groups
were 0.87, 0.72, and 0.51, respectively. The was 0.053. Reconstruct the analysis of
variance summary table. What can you conclude?
11.23 In Exercise 11.22 the data were transformed from their original units, which were in
seconds. What effect would this have on the shape of the distributions?
11.24 Would a transformation of Eysenck’s data in Table 11.2 be useful in terms of equalizing the
variances? What transformation would you suggest applying, if any?
11.25Suppose that we wanted to run a study comparing recall of nouns and verbs. We present
each subject with 25 nouns or 25 verbs and later ask for recall of the list. We look at both
differences between parts of speech and between different words within the category of
“noun.” What variable is a fixed variable and what is a random variable?
11.26 Give an example of a study in which the main independent variable would be a random variable.
11.27 Davey, Startup, Zara, MacDonald, and Field (2003) were interested in the role of mood on
the degree of compulsive checking in which a person engaged. (Compulsive checking is in-
volved in a number of psychopathologies.) Three groups of 10 participants each listened to
music designed to induce a positive, negative, or neutral mood. They were then asked to
“list as many things around your home that you should check for safety or security reasons
before you go away for three weeks.” The dependent variable was the number of things
listed. The actual data follow.
MSerrorh^2 v^2