Generalizability of Performance Assessments


  • Robert L. Brennan is now E. R Lindquist Professor of Educational Measurement at 334A Lindquist Center, University of Iowa, Iowa City, IA 52242. His specializations are generalizability theory, equating, and scaling.

  • Eugene G. Johnson is a Principal Research Scientist, Educational Testing Service, 02-1: Princeton, NJ 08541. His specializations are statistics and educational measurement.


How can the contributions of raters and tasks to error variance be estimated? Which source of error variance is usually greater? Are interrater coefficients adequate estimates of reliability? What other facets contribute to unreliability in performance assessments?