It is demonstrated that the popular three-parameter logistic model can lead to markedly inaccurate individual ability level estimates for mixture populations. A theoretically and empirically important setting is initially considered where (a) in one of two subpopulations (latent classes) the two-parameter logistic model holds for each item in a…

What is validity? A simple question but apparently one with many answers, as Paul Newton highlights in his review of the history of validity. The current definition of validity, as entertained in the 1999 "Standards for Educational and Psychological Testing" is indeed a consensus, one between the classical notion of attributes, and measures…

The 1999 "Standards for Educational and Psychological Testing" defines validity as the degree to which evidence and theory support the interpretations of test scores entailed by proposed uses of tests. Although quite explicit, there are ways in which this definition lacks precision, consistency, and clarity. The history of validity has taught us…

Standard setting is a systematic process that uses a combination of judgmental and empirical procedures to make recommendations about where on the score continuum "cut scores" should be placed. Cut scores divide the score scale into categories consistent with the descriptions of student performance associated with multiple levels of achievement.…