Item Function Characteristics and Dimensionality for Alternative Response Formats in Mathematics

Abstract

The purpose of this study was to investigate the technical properties of stem-equivalent mathematics items differing only with respect to response format. Using socio- economic factors to define the strata, a proportional stratified random sample of 1,366 Connecticut sixth-grade students were administered one of three forms. Classical item analysis, dimensionality assessment, item response theory goodness-of-fit, and an item bias analysis were conducted. Analysis of variance and confirmatory factor analysis were used to examine the functioning of the items presented in the three different formats. It was found that, after equating forms, the constructed-response formats were somewhat more difficult than the multiple-choice format. However, there was no significant difference across formats with respect to item discrimination. A differential item functioning (DIF) analysis was conducted using both the Mantel-Haenszel procedure and the comparison of the item characteristic curves. The DIF analysis indicated that the presence of bias was not greatly affected by item format; that is, items biased in one format tended to be biased in a similar manner when presented in a different format, and unbiased items tended to remain so regardless of format.