Chapter 8, Problem 121P

The Diabetes Prevention Study was a randomized study conducted in Finland in which middle-aged participants (mean age 55 years) with impaired glucose tolerance (IGT) were enrolled [17]. Study participants, who had high-normal glucose levels, were randomized to either an intervention group or a control group. People in the intervention group were encouraged to (a) reduce weight, (b) reduce fat intake, (c) increase fiber intake, and (d) increase hours per week of exercise. They also underwent intensive individuallevel counseling to reduce risk-factor levels. People in the control group received pamphlets with general information concerning diet and exercise but did not receive individual counseling. Data regarding changes in weight after 1 year are shown in Table 8.30.

Table 8.30 Mean weight change by treatment group among people with IGT in the Diabetes Prevention Study

*Follow-up weight – baseline weight.

For the purposes of this problem, for any degrees of freedom (d) ≥ 200, assume that td ≅ N (0, 1) distribution.

What test can be used to assess mean changes in weight in the intervention group?