Article

On the Performance of the lZ Person-Fit Statistic

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Abstract

Person-fit measurement refers to statistical methods used to detect improbable item-score patterns. This study investigates the detection effectiveness of the z l statistic, which is one of the most popular and powerful person-fit statistics in the literature to date. The contributions of the present study are three-fold. First, the simulation results show that the detection power of the z l statistic is largely hinged on test characteristics, particularly the test difficulty. Therefore, the z l statistic should be used with caution in an operational testing environment. Second, this paper provides a clear explanation for the poor performance of the z l statistic under certain situations. The third objective is to present a summary of the patterns and conditions for which the z l statistic is not recommended for the detection of aberrancy. This can be used as a checklist for implementation purposes. Accessed 41,380 times on https://pareonline.net from December 05, 2007 to December 31, 2019. For downloads from January 1, 2020 forward, please click on the PlumX Metrics link to the right.

Keywords: Statistical Analysis

How to Cite:

Armstrong, R. D., Stoumbos, Z. G., T., K. M. & Shi, M., (2007) “On the Performance of the lZ Person-Fit Statistic”, Practical Assessment, Research, and Evaluation 12(1): 16. doi: https://doi.org/10.7275/xz5d-7j62