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11.17 COMMUNICATING THE RESULTS
Six students from a local community college matched for their driving expe-
rience participated in this within-subjects design. Students drove a sport car
and an SUV at different times after having either zero, one, or three alcoholic
drinks. The dependent variable was driving errors made. All effects met the
assumption of sphericity as tested by Mauchly's procedure.
No significant main effect was found for type of vehicle,
F
(1, 10)
=
2
.
78,
p
>.
05, but a significant effect was found for number of drinks,
F
(2, 10)
=
2
157
.
39,
p
<.
05,
η
=
.
77. However, the two-way interaction was found to be
2
significant,
F
(2, 10)
08.
The graph of the interaction is presented in Figure 11.2. Simple effects
analysis indicated that driving errors increased steadily as a function of alcohol
consumption when they were driving a sport car. Errors made while driving
an SUV increased comparably to the sport car up to one drink but leveled off
from one to three drinks.
=
8
.
53,
p
<.
05,
η
=
.
CHAPTER 11 EXERCISES
11.1.
Researchers are interested in the effects of both auditory and visual
stimulation on children's problem solving ability. Fifth grade children are
presented with rock (
a
1
)andhiphop(
a
2
)musicinroomspaintedinred
(
b
1
), white (
b
2
), or yellow (
b
3
) while solving ten anagram problems in each
treatment combination. The dependent variable is the number of correct
solutions. The data are as follows:
a
1
a
2
Subject
b
1
b
2
b
3
b
1
b
2
b
3
1 4 7 5 2 7 5
2 3 7 6 2 8 6
3 3 8 7 2 9 5
4 2 8 7 3 7 6
5 1 6 6 1 8 5
a. Conduct an ANOVA on these data by hand and with SPSS or SAS.
b. If the interaction is statistically significant, perform a simple effects
analysis and multiple comparisons tests by hand and with SPSS or
SAS.
11.2.
Consider the hypothetical 3
×
3 factorial data set below. The nine
treatment combinations had
n
=
4 participants receiving all treatments in
a randomized order.
a
1
a
2
a
3
Subject
b
1
b
2
b
3
b
1
b
2
b
3
b
1
b
2
b
3
1
4 7 2 0 7 5 1 8 9
2
6
9
14
10
17
9
20
17
19
3
8
8
14
14
20
9
24
17
20
4
8
6
9
19
20
8
19
15
21
