Dimensionality Assessment in Forced-Choice Questionnaires: First Steps Toward an Exploratory Framework.

Forced-choice (FC) questionnaires have gained increasing attention as a strategy to reduce social desirability in self-reports, supported by advancements in confirmatory models that address the ipsativity of FC test scores. However, these models assume a known dimensionality and structure, which can be overly restrictive or fail to fit the data adequately. Consequently, exploratory models can be required, with accurate dimensionality assessment as a critical first step. FC questionnaires also pose unique challenges for dimensionality assessment, due to their inherently complex multidimensional structures. Despite this, no prior studies have systematically evaluated dimensionality assessment methods for FC data. To fill this gap, the present study examines five commonly used methods: the Kaiser Criterion, Empirical Kaiser Criterion, Parallel Analysis (PA), Hull Method, and Exploratory Graph Analysis. A Monte Carlo simulation study was conducted, manipulating key design features of FC questionnaires, such as the number of dimensions, items per dimension, response formats (e.g., binary vs. graded), and block composition (e.g., inclusion of heteropolar and unidimensional blocks), as well as factor loadings, inter-factor correlations, and sample size. Results showed that the Maximal Kaiser Criterion and PA methods outperformed the others, achieving higher accuracy and lower bias. Performance improved particularly when heteropolar or unidimensional blocks were included or when the questionnaire length increased. These findings emphasize the importance of thoughtful FC test design and provide practical recommendations for improving dimensionality assessment in this format.