The BIFACTOR program estimates the bifactor model for ordinal and dichotomous data. The bifactor model can be used to represent factorial structures for many types of psychological and educational tests, since they can exhibit a general factor and one or more group or method factors. The bifactor structure results from the constraint that each item has a nonzero loading on the primary dimension and, at most, one of the group factors.

Authors list:
Robert D. Gibbons and Donald Hedeker

Gibbons RD, Hedeker D. BIFACTOR: A computer program for full-information item bifactor models for analysis of binary and ordinal response data., 2007.


In Full-Information Item Bifactor Analysis of Graded Response Data View PDF, Gibbons et al. develop estimation procedures for fitting the graded response model when the data follow the bifactor structure. A limited-information solution based on polychoric correlations using robust WLS, which is available in Mplus software for the full-information approach, is presented as an alternate estimation method for the bifactor model. Read a comparison of estimates obtained from Mplus and BIFACTOR. View PDF

Technical Report: The Added Value of Multidimensional IRT Models View PDF
Robert D. Gibbons, Jason C. Immekus, and R. Darrell Bock

Didactic Workbook: The Added Value of Multidimensional IRT Models View PDF
Robert D. Gibbons, Jason C. Immekus, and R. Darrell Bock

System requirements:
Microsoft Windows 2000, Windows XP or Windows 7

Download contents:
The downloaded contains the following files:

BIFACTOR.BAT - double-click this file to run the BIFACTOR program
README.TXT - important notes on the BIFACTOR program
TEST1.DEF through TEST5.DEF - input files for POLYBIF.EXE
bi-factor-rating scale-theta-y1at0.002.inp - Mplus program setup file
bi-factor-rating scale-theta-y1at0.002.out - Mplus program output file

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  Last updated August 15, 2016. Copyright © 2003-2016 Center for Health Statistics. All Rights Reserved.

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