Use of the Unbalanced Nested ANOVA To Examine the Relationship of Class Size to Student Ratings of Instructional Quality.

This report examines how class size and course motivation are related to evaluation results, its purpose being to provide a comparison of rating differences on the Instructor and Course Evaluation System (ICES). ICES offers faculty a computer-based catalog of over 1,000 survey items. The article is based on a study that sought to extend the ICES research by using an unbalanced nested ANOVA to analyze the effects of five factors: course motivation, course level, class size, academic discipline, and individual class differences on (1) student ratings of instructors; and (2) student ratings of overall course quality. The results of the ANOVA showed that course motivation, course level, class size, discipline, and individual class do influence student ratings of both teaching effectiveness and course quality. Different combinations of course motivation, level, and discipline displayed different patterns of student ratings. The significant two-way interactions (in which one of the factors alters the effect of the other) were course motivation and discipline, course level and class size, and course level and discipline. Generally, ratings of elective courses were higher than those of mixed courses, and ratings of mixed courses were higher than those of required courses. Higher level classes had higher ratings than lower level ones. Contains 27 references, 10 figures, and 9 tables. (RJM)