15.12 Chemotherapy Cancer treatment by means of chemicals-chemotherapy-kills both cancerous and normal cells. In some instances, the toxicity of the cancer drug-that is, its effect on normal cells can be reduced by the simultaneous injection of a second drug. A study was conducted to determine whether a particular drug injection reduced the harmful effects of a chemotherapy treatment on the survival time for rats. Two randomly selected groups of 12 rats were used in an experiment in which both groups, call them A and B, received the toxic drug in a dose large enough to cause death, but in addition, group B received the antitoxin, which was to reduce the toxic effect of the chemotherapy on normal cells. The test was terminated at the end of 20 days, or 480 hours. The survival times for the two groups of rats, to the nearest four hours, are shown in the table. Do the data provide sufficient evidence to indicate that rats receiving the antitoxin tend to survive longer after chemotherapy than those not receiving the antitoxin? Use the Wil- coxon rank sum test with a = 0.05.

Transcribed Image Text:

Chemotherapy Only Chemotherapy plus Drug A 84 B 140 128 184 168 368 92 96 184 480 92 188 76 480 104 244 72 440 180 380 144 480 120 196