This study investigated the distributional properties of the standardized residual that is commonly used in the Rasch model calibration program to develop various indices of item and person fit. The power of the standardized residual to detect measurement disturbances is also addressed. (TJH)

In all latent trait models there is an equation which describes the probabilistic outcome of the interaction of a person with a known ability and an item with a known difficulty. This modeled outcome can be compared to the observed outcome, and the residuals can be summed over the items to assess the fit of the person to the model. Various…

There have been many attempts to formulate a procedure for extracting information from incorrect responses to multiple choice items, i.e., the assessment of partial knowledge. The results of these attempts can be described as inconsistent at best. It is hypothesized that these inconsistencies arise from three methodological problems: the…

Standard maximum likeliheed estimation was compared using two forms of robust estimation, BIWEIGHT (based on Tukey's Biweight) and AMTJACK (AMT-Robustified Jackknife), and Rasch model person analysis. The two procedures recovered the generating parameters, but Rasch person analysis also helped to identify the nature of a response disturbance. (GDC)

To analyze test item and person interactions according to the Rasch Model, 822 incoming community college freshman were administered the New Jersey Basic Skills Placement Test. The Logical Relationships and Elementary Algebra subtests were chosen to examine the effect of differing average item difficulty on descriptions of fit statistics and on…

Measurement disturbances, such as guessing, startup, and plodding, often result in an examinee's ability being either over- or under-estimated by the maximum likelihood estimation employed in latent trait psychometric models. Several authors have suggested methods to lessen the impact of unexpected responses on the ability estimation process. This…