The use of discrete categorical formats to assess psychological traits has a long-standing tradition that is deeply embedded in item response theory models. The increasing prevalence and endorsement of computer- or web-based testing has led to greater focus on continuous response formats, which offer numerous advantages in both respondent…

Item response tree (IRTree) models are a flexible framework to control self-reported trait measurements for response styles. To this end, IRTree models decompose the responses to rating items into sub-decisions, which are assumed to be made on the basis of either the trait being measured or a response style, whereby the effects of such person…

This study develops a theoretical model for the costs of an exam as a function of its duration. Two kind of costs are distinguished: (1) the costs of measurement errors and (2) the costs of the measurement. Both costs are expressed in time of the student. Based on a classical test theory model, enriched with assumptions on the context, the costs…

This inquiry is focused on three indicators of the precision of measurement--conditional on fixed values of ?, the latent variable of item response theory (IRT). The indicators that are compared are (1) The traditional, conditional standard errors, s(eX|?) = CSEM; (2) the IRT-based conditional standard errors, s[subscript irt](eX|?)=C[subscript…

Cronbach's coefficient alpha is a widely used reliability measure in social, behavioral, and education sciences. It is reported in nearly every study that involves measuring a construct through multiple items. With non-tau-equivalent items, McDonald's omega has been used as a popular alternative to alpha in the literature. Traditional estimation…

This paper considers some appropriate and inappropriate uses of coefficient kappa and alternative kappa-like statistics. Discussion is restricted to the descriptive characteristics of these statistics for measuring agreement with categorical data in studies of reliability and validity. (Author)

The usual formulas for the reliability of differences between two test scores are based on the assumption that the error scores are uncorrelated. Formulas are presented for the general case where this assumption is unnecessary. (Author/JKS)

Study based on F. M. Lord's arguments in 1957 and 1959 that tests of the same length do have the same standard error of measurement. (CB)

Unreliable profiles impose the difficulty that ordinal and interval relations among the individual's scores become uncertain or unstable. A profile reliability coefficient is derived to estimate the relative expected extent of this ordinal and interval "inversion" for any profile of K measures. (Author/DWH)

Author supports the credibility of the propositions that: (1) the true component of a score is proportional to the number of equivalent elements that contribute to it. And, (2) the error component of a score is proportional to the square root of the number of equivalent elements that contribute to it. (Author/MB)

This paper summarizes much of the available information concerning the reliability and validity of the Tests of General Educational Development (GED Tests). The data suggest that the results are sufficiently reliable for continued use and that the validity evidence generally supports the intended uses of the tests. (Author/LMO)

A derivation of a formula for the stability coefficient is presented and discussed in terms of test reliability over time. (PR)

This paper discusses the basic theory underlying confidence limits and presents reasons why psychologists should incorporate confidence ranges in their psychodiagnostic reports. Four methods for establishing confidence limits are compared. Three of the methods involve estimated true scores, and the fourth is the standard error of measurement…