Preventing halo bias in grading the work of university students

Abstract

Experts have advocated anonymous marking as a means of minimizing bias in subjective student assessment. In the present study, 159 faculty members or teaching assistants across disciplines were randomly assigned (1) to grade a poor oral presentation of a university student, (2) to grade a good oral presentation of the same student, or (3) not to grade any oral presentation of the student. All graders then assessed the same written work by the student. A linear-contrasts analysis showed that, as hypothesized, the graders assigned significantly higher scores to written work following the better oral presentation than following the poor oral presentation, with intermediate scores for the written work of the student whose oral presentation was not seen by the graders. The results provide evidence of a halo effect in that prior experience with a student biased the grading of written work completed by the student. The findings suggest that keeping students anonymous, as in the condition with no knowledge of the student’s performance in the oral presentation, helps prevent bias in grading.