Biserial weights: A new approach to test item option weighting

Abstract

Option weighting is an alternative to increasing test length as a means of improving the reliability of a test. The effects on test reliability of option weighting procedures, including two procedures not previously reported, were compared in two empirical studies using four independent sets of items. In all cases Guttman weights and Biserial weights (based on the Brogden Biserial or Cleman’s Lambda coefficient) were superior to Number Right and Correction for Guessing weights. Overall, Biserial weights appeared to be superior to Guttman weights.