A new method for studying the halo effect in teachers' judgement and its antecedents: Bringing out the role of certainty.

The results of both studies revealed the presence of a halo effect in teachers' judgements for each measure used (i.e., comparison of correlations, factorial analyses, and the new measure comparing variance scores), as the teachers' judgements were more homogeneous than the students' actual achievement levels. Furthermore, using the new measure, the second study revealed that high judgement certainty resulted in a stronger halo effect.