A Weibull-Link Response Model for Measuring Unipolar-Skewed Constructs With Continuous Responses

Identifier:  imarina:9633024

Handle: https://hdl.handle.net/20.500.11797/imarina9633024

Authors:  Ferrando PJ; Morales-Vives F; Casas JM; Navarro-González D

Abstract:
In certain noncognitive applications attempts are made to measure unipolar traits expected to have positively skewed distributions in the target populations, two conditions that clash head-on with the bipolarity and normality assumptions on which most standard IRT models are based. Unipolar-skewed models are an alternative to be used in these conditions, and we propose here a model intended for double-bounded continuous response items in which: (a) the link function or item response function is a cumulative Weibull curve, and (b) the initial latent distribution is lognormal. The model is simple, has desirable psychometric properties, and, conceptually, provides a plausible account of the response functioning. We propose a full development which has been also implemented in a free R program. Moreover, an empirical study is included, and its results show that the model behaves appropriately when used with real data, delivering the anticipated accuracy and external validity outcomes.