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Activity Number: 68
Type: Contributed
Date/Time: Sunday, August 3, 2014 : 4:00 PM to 5:50 PM
Sponsor: ENAR
Abstract #313794 View Presentation
Title: Dimensionality Assessment for Polytomous Item Instrument
Author(s): Tan Li*+
Companies: Florida International University
Keywords: Dimensionality ; IRT ; Psychometrics ; Self-report assessment
Abstract:

In the field of public health, many research areas, such as HIV preventions, health care decisions, and clinical trials, frequently depend on individual self reported assessments. Item response theory (IRT) modelling offers a powerful tool for evaluating instruments both at the item and scale level. Unidimensionality is the main assumption underlying the widely used IRT models. It assumes that the psychometric instrument only measures a single latent trait. Practically, the violation indicates that it may be biased to report a single score for an instrument. The proposed conditional-covariance-based nonparametric dimensionality assessment method in this paper, Poly-NEWDIM (PND), in conjunct with the proposed conditional covariance based subset selection method, HCPND, demonstrated closer to nominal Type I error control and better power than previous methods in the previous simulation studies. The purpose of this paper is to evaluate the proposed method under more complex data structures, such as fan structures, and more dimensions (3 or 4), as well as a real measurement in public health area.


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