Russel-Research-Method-in-Anthropology

120 Chapter 5
Time 1 Time 2
Assignment Pretest
Intervention Posttest
Group 1 R O X O
1 2
Group 2 R O O
Figure 5.1a. The classic design: Two-group pretest-posttest.
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and posttest scores for the first group might have occurred anyway, even if the
intervention hadn’t taken place.
Patricia Chapman (Chapman et al. 1997) wanted to educate young female
athletes about sports nutrition. She and her colleagues worked with an eightteam
girl’s high school softball league in California. There were nine 14–18
years olds on each team, and Chapman et al. assigned each of the 72 players
randomly to one of two groups. In the treatment group, the girls got two, 45-
minute lectures a week for 6 weeks about dehydration, weight loss, vitamin
and mineral supplements, energy sources, and so on. The control group got no
instruction.
Before the program started, Chapman et al. asked each participant to complete
the Nutrition Knowledge and Attitude Questionnaire (Werblow et al.
1978) and to list the foods they’d eaten in the previous 24 hours. The nutrition
knowledge-attitude test and the 24-hour dietary recall test were the pretests
in this experiment. Six weeks later, when the program was over, Chapman et
al. gave the participants the same two tests. These were the posttests. By comparing
the data from the pretests and the posttests, Chapman et al. hoped to
test whether the nutrition education program had made a difference.
The education intervention did make a difference—in knowledge, but not
in reported behavior. Both groups scored about the same in the pretest on
knowledge and attitudes about nutrition, but the girls who went through the
lecture series scored about 18 points more (out of 200 possible points) in the
posttest than did those in the control group.
However, the program had no effect on what the girls reported eating. After
6 weeks of lectures, the girls in the treatment group reported consuming 1,892
calories in the previous 24 hours, while the girls in the control group reported
1,793 calories. A statistical dead heat. This is not nearly enough for young
female athletes, and the results confirmed for Chapman what other studies had
already shown—that for many adolescent females, the attraction of competitive
sports is the possibility of losing weight.
This classic experimental design is used widely to evaluate educational pro-