39. A small pilot study is conducted to investigate the effect of a nutritional supplement on total body
weight. Six participants agree to take the nutritional supplement. To assess its effect on body weight,
weights are measured before starting the supplementation and then after 6 weeks. The data are shown
below. Is there a significant increase in body weight following supplementation? Run the test at a 5% level
of significance.

40. A small pilot study is run to compare a new drug for chronic pain to one that is currently available.
Participants are randomly assigned to receive either the new drug or the currently available drug and to
report improvement in pain on a 5-point ordinal scale: 1 = Pain is much worse, 2 = Pain is slightly worse,
3 = No change, 4 = Pain improved slightly, 5 = Pain much improved. Is there a significant difference in
self-reported improvement in pain? Use the Mann-Whitney
U
test with a 5% level of significance.

41. The following table was presented in an article summarizing a study to compare a new drug to a
standard drug and to a placebo.
Characteristic*
New Drug
Standard Drug
Placebo
p
Age, years
45.2 (4.8)
44.9 (5.1)
42.8 (4.3)
0.5746
% Female
51%
55%
57%
0.1635
Annual Income, $000s
59.5 (14.3)
63.8 (16.9)
58.2 (13.6)
0.4635

% with Insurance
87%
65%
82%
0.0352
Disease Stage
0.0261
Stage I
35%
18%
33%
Stage II
42%
37%
47%
Stage III
23%
51%
20%
*Table entries and Mean (SD) or %
Are there any statistically significant differences in the characteristics shown among the treatments?
Justify your answer
42. What is the appropriate statistical test to assess whether there is an association between obesity
status (normal weight, overweight, obese) and 5-year incident cardiovascular disease (CVD)? Suppose
each participant’s obesity status (category) is known along with whether they develop CVD over the next
5 years or not.
43. A random sample of 8 adults aged 30 years were asked how much they spent on medical costs in the
year 2009. Using the following data, compute the sample mean, the sample standard deviation, the
sample median, and the first and third quartiles.

44. The table below summarizes baseline characteristics of patients participating in a clinical trial. a) Are
there any statistically significant differences in baseline characteristics between treatment groups? Justify
your answer.
P