A comparison of methods for plate waste determinations

Plate waste studies have traditionally been used to evaluate behavior change in nutrition education programs. Identical menus are served both before and after the implementation of curriculum. Theoretically, students will internalize nutrition information, and there will be less waste in the post-test phase. In this study, two methods for determining plate waste were compared using 343 students from six schools in a pretest/post-test treatment vs. control group design. One method consisted of actual weighing of waste using gram scales. The second method utilized visual estimation of the waste expressed on a 6-point scale. Correlations between the two methods were high. However, when statistical analysis was done to determine differences between groups, it was found that the visual estimation method was not always so sensitive in detecting differences as was the weighed food method. The visual method was also found to be more difficult to interpret. It is suggested that while there are advantages to the visual estimation method, its use be limited to informal studies in which broad generalizations will not be made as to the effectiveness of nutrition education programs.