What percentage of the placebo group would be expected to show a change of not more than

Question:

What percentage of the placebo group would be expected to show a change of not more than 0.30 mg/dL?

Cancer

A treatment trial is proposed to test the efficacy of vitamin E as a preventive agent for cancer. One problem with such a study is how to assess compliance among participants. A small pilot study is undertaken to establish criteria for compliance with the proposed study agents. In this study, 10 patients are given 400 IU/day of vitamin E and 10 patients are given similar-sized placebo capsules over a 3-month period. Their serum vitamin E levels are measured before and after the 3-month period, and the change (3-month €“ baseline) is shown in Table 5.2.

Table 5.2: Change in serum vitamin E (mg/dL) in pilot study

Group Mean sd Vitamin E 0.48 0.80 10 Placebo 0.05 0.16 10