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The Relationship Between Item Exposure and Test Overlap in Computerized Adaptive Testing
Author(s) -
Chen ShuYing,
Ankenmann Robert D.,
Spray Judith A.
Publication year - 2003
Publication title -
journal of educational measurement
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.917
H-Index - 47
eISSN - 1745-3984
pISSN - 0022-0655
DOI - 10.1111/j.1745-3984.2003.tb01100.x
Subject(s) - computerized adaptive testing , test (biology) , item response theory , psychology , test validity , statistics , computer science , psychometrics , clinical psychology , mathematics , biology , paleontology
The purpose of this article is to present an analytical derivation for the mathematical form of an average between‐test overlap index as a function of the item exposure index, for fixed‐length computerized adaptive tests (CATs). This algebraic relationship is used to investigate the simultaneous control of item exposure at both the item and test levels. The results indicate that, in fixed‐length CATs, control of the average between‐test overlap is achieved via the mean and variance of the item exposure rates of the items that constitute the CAT item pool. The mean of the item exposure rates is easily manipulated. Control over the variance of the item exposure rates can be achieved via the maximum item exposure rate (r max ). Therefore, item exposure control methods which implement a specification of r max (e.g., Sympson & Hetter, 1985) provide the most direct control at both the item and test levels.