Using a single score for summative teacher evaluation by students

In spite of the hundreds of studies done on teacher evaluation by student ratings, there are still several major controversial issues of how to construct evaluation instruments that best serve their purpose. The present study contributes to one of the ongoing debates of recent years that addresses the number of teaching dimensions to be considered in decision making, namely, whether to use a single score or multiple scores for teacher evaluation. The study demonstrates using a short form on which the global score "overall teaching performance" can almost perfectly predict the mean of all teacher-attribute items. The questionnaire used in this study was administered eight times-twice a semester for two years-for all faculty members and TAs in the departments of physics and chemistry at Tel Aviv University. The composition of teacher attribute items was different for the faculty members and TAs, reflecting their different teaching functions-lectures versus recitation problem solving. Results show that while for the faculty the global score can simply replace the mean of all instructor-attribute items and serve as a single score that faithfully represents all dimensions of teacher ratings, for the TAs, a linear transformation is needed.