Fitting a Thurstonian IRT model to forced-choice data using Mplus

Behav Res Methods. 2012 Dec;44(4):1135-47. doi: 10.3758/s13428-012-0217-x.

Abstract

To counter response distortions associated with the use of rating scales (a.k.a. Likert scales), items can be presented in a comparative fashion, so that respondents are asked to rank the items within blocks (forced-choice format). However, classical scoring procedures for these forced-choice designs lead to ipsative data, which presents psychometric challenges that are well described in the literature. Recently, Brown and Maydeu-Olivares (Educational and Psychological Measurement 71: 460-502, 2011a) introduced a model based on Thurstone's law of comparative judgment, which overcomes the problems of ipsative data. Here, we provide a step-by-step tutorial for coding forced-choice responses, specifying a Thurstonian item response theory model that is appropriate for the design used, assessing the model's fit, and scoring individuals on psychological attributes. Estimation and scoring is performed using Mplus, and a very straightforward Excel macro is provided that writes full Mplus input files for any forced-choice design. Armed with these tools, using a forced-choice design is now as easy as using ratings.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Choice Behavior*
  • Humans
  • Judgment
  • Models, Psychological*
  • Psychometrics / methods
  • Surveys and Questionnaires