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
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
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.
Annual Income, $000s