1.5 Twenty adult males between the ages of 30 and
40 participated in a study to evaluate the effect of a
specific health regimen involving diet and exercise on
the blood cholesterol. Ten were randomly selected to
be a control group, and ten others were assigned to
take part in the regimen as the treatment group for a
period of 6 months. The following data show the reduction
in cholesterol experienced for the time period
for the 20 subjects:
Control group: 7 3 −4 14 2
5 22 −7 9 5
Treatment group: −6 5 9 4 4
12 37 5 3 3
(a) Do a dot plot of the data for both groups on the
same graph.
(b) Compute the mean, median, and 10% trimmed
mean for both groups.
(c) Explain why the difference in means suggests one
conclusion about the effect of the regimen, while
the difference in medians or trimmed means suggests
a different conclusion.
JAWABAN
1.5
(a) Control group: 7 3 −4 14 25 22 −7 95
Treatment group: −6 5 9 4412 37 5 3 3
(b) Control: ¯x = 5.60, ˜x = 5.00, ¯xtr(10) = 5.13.
Treatment: ¯x = 7.60, ˜x = 4.50, ¯xtr(10) = 5.63.
(c) The extreme value of 37 in the treatment group plays a strong leverage role for the mean calculation.
