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ERIC Number: ED478076
Record Type: Non-Journal
Publication Date: 2003-Apr
Pages: 26
Abstractor: N/A
Reference Count: N/A
ISBN: N/A
ISSN: N/A
Exploring a Stable Difficulty Index for Polytomous Essay Items.
Zhu, Renbang; Yu, Feng
To ensure fairness, it is of critical importance that testing programs make sure that essay items given to examinees are equivalent in difficulty. The purpose of this study was to evaluate the stability and accuracy of a logistic regression based polytomous essay difficulty index. Preliminary results from a simulation study (9 conditions with a 100 replications of each condition) and real data from prior studies suggest that the developed index exhibits three desired statistical properties. First, the index was sensitive to the change of essay difficulty. In addition, the index could be computed easily through logistic regression analysis based on a relatively small sample size. Finally, the index was reasonably stable across different examinee ability distributions. However, the degree of stability was not as good as expected, particularly when examinees' ability distributions differed markedly from the normal condition. Therefore, further modification of the difficulty index and analyses needs to be done before the index can be recommended for practical use.(SLD)
Publication Type: Reports - Research; Speeches/Meeting Papers
Education Level: N/A
Audience: N/A
Language: English
Sponsor: N/A
Authoring Institution: N/A