The following study discusses the efforts to reduce
body weights of 20 moderately overweight student volunteers by
interventions involving diet, increased physical activity, or
both. The students are randomly assigned to four groups:
Group 1: controls; no change in diet or physical activity
Group 2: diet; reduction in caloric intake
Group 3: physical activity; increase in leisure-time activity
level
Group 4: diet plus physical activity; receive both the
interventions of group 2 and of group 3
After 3 months, weight reduction is
measured, with the following results, positive values, for example,
4 indicating a 4-lb weight loss:
Group 1
(controls):
5 -2 3
2 0
Group 2 (diet
only):
2 8 4
12 4
Group 3 (physical activity only):
8 0 2
6 2
Group 4
(both):
12 6 15
8 10
a) Does this data suggest a
significant difference between groups? (Done by hand, show
all your work!)
b) Verify your work in part a)
using SAS. (print off your SAS code and output and highlight key
values. State why this verifies part a). )
c) If appropriate, use a
Multiple Comparison procedure taught in lecture that has the
highest statistical power. (Complete by hand)
d) If appropriate, show the
Multiple Comparison procedure done in part c) using SAS.
(print off your SAS code and output and highlight key values.
Explain why this verifies part c) )
e) Notice that some groups receive a diet and others do
not. Construct this contrast to see if there is a significant
difference, perform the significance test, and summarize the
results. (This must be done by hand).