Response shift bias: A problem in evaluating nutrition training using self-report measures

The Cooperative Extension Service has been a key partner in the design, imp lementation, and evaluation of school nutrition training. To evaluate the e ffectiveness of their training and the effects of response shift bia, on ou tcomes using a self-report measure. 162 foodservice staff from eight rural schools participated in this food-handling behavior study. Nutrition staff were assigned to one of two treatment groups or to the control group. Two d ifferent evaluation designs (pre-test/post-test and then/post) were used. T he then/post design asks participants to first report their behavior or und erstanding as a result of the training (post) and then to retrospectively r eport this behavior before the training. The then/post evaluation design pr ovided more significant character data than did the traditional pretest/pos t-test design, indicating that a response shift occurred. Such differences in evaluation findings suggest that the educational benefit of such trainin gs may he underestimated when using the traditional pre/post evaluation des ign.