ERIC Number: ED395012
Record Type: Non-Journal
Publication Date: 1989-Sep
Reference Count: N/A
Statistical Approaches to the Study of Item Difficulty.
Olson, John F.; And Others
Traditionally, item difficulty has been defined in terms of the performance of examinees. For test development purposes, a more useful concept would be some kind of intrinsic item difficulty, defined in terms of the item's content, context, or characteristics and the task demands set by the item. In this investigation, the measurement literature was surveyed for statistical approaches that might be applied to the study of item difficulty. Two broad methodological approaches were identified, exploratory and confirmatory approaches. Exploratory methods are those that attempt to categorize or cluster items that appear to measure similar abilities, that function in a similar manner in order to determine their common characteristics, and that differentiate them from other items not in the cluster. Confirmatory methods would be applied to test hypotheses developed from exploratory results or from psychological theory. The final section of the paper describes analyses using real test data that assessed the usefulness of two exploratory methods. Data from the NTE specialty area test for teacher certification in social studies for 1,748 examinees were used to evaluate full-information factor analysis and a measure of local item independence. The analyses indicate the usefulness of exploratory methods. (Contains 53 references.) (Author/SLD)
Publication Type: Reports - Evaluative
Education Level: N/A
Authoring Institution: Educational Testing Service, Princeton, NJ.