Implications of three causal models for the measurement of halo error

The appropriateness of a traditional correlational measure of halo error (the difference between dimensional rating intercorrelations and dimensional true score intercorrelations) is reexamined in the context of three causal models of halo error. Mathematical derivations indicate that the traditional correlational measure typically will underestimate halo error in ratings and can suggest no halo error or even "negative" halo error when positive halo error actually occurs. A corrected correlational measure is derived that avoids these problems, and the traditional and corrected measures are compared empirically. Results suggest that use of the traditional correlational measure of halo error be discontinued. Index terms: halo, halo effect, halo error, performance ratings, rating accuracy, rating errors