Coefficients alpha, beta, omega, and the glb: Comments on Sijtsma
W Revelle, RE Zinbarg�- Psychometrika, 2009 - Springer
Psychometrika, 2009•Springer
There are three fundamental problems in Sijtsma (Psychometrika, 2008):(1) contrary to the
name, the glb is not the greatest lower bound of reliability but rather is systematically less
than ω t (McDonald, Test theory: A unified treatment, Erlbaum, Hillsdale, 1999),(2) we agree
with Sijtsma that when considering how well a test measures one concept, α is not
appropriate, but recommend ω t rather than the glb, and (3) the end user needs procedures
that are readily available in open source software.
name, the glb is not the greatest lower bound of reliability but rather is systematically less
than ω t (McDonald, Test theory: A unified treatment, Erlbaum, Hillsdale, 1999),(2) we agree
with Sijtsma that when considering how well a test measures one concept, α is not
appropriate, but recommend ω t rather than the glb, and (3) the end user needs procedures
that are readily available in open source software.
Abstract
There are three fundamental problems in Sijtsma (Psychometrika, 2008): (1) contrary to the name, the glb is not the greatest lower bound of reliability but rather is systematically less than ω t (McDonald, Test theory: A unified treatment, Erlbaum, Hillsdale, 1999), (2) we agree with Sijtsma that when considering how well a test measures one concept, α is not appropriate, but recommend ω t rather than the glb, and (3) the end user needs procedures that are readily available in open source software.
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