Investigating Item Exposure Control Methods in Computerized Adaptive Testing
Year: 2015 Vol: 15 Number: 1
This study aims to investigate the effects of item exposure control methods on measurement precision and on test security under various item selection methods and item pool characteristics. In this study, the Randomesque (with item group sizes of 5 and 10), Sympson-Hetter, and Fade-Away methods were used as item exposure control methods. Moreover, in order to establish a comparison baseline for other methods, the noexposure control condition was also included in the research. As item selection methods, Maximum Fisher Information, a-Stratification, and Gradual Maximum Information Ratio were employed. While a parameters were generated from a uniform distribution ranging between 0.50 and 2.00 and c parameters were generated from a uniform distribution ranging between 0.05 and 0.20 for both item pools, b parameters were generated from a uniform distribution ranging between -3.00 and +3.00 for medium difficulty item pool, and from a standard normal N(2, 1.5) distribution for high difficulty item pool. Based on the research findings, there were no great differences between the values of indicators used in determining measurement precision when the item exposure control methods were used. On the other hand, in terms of test security, it was found that in general, the Fade-Away Method for controlling item exposure yielded better results than did the other methods in reducing the skewness of item pool utilization and the test overlap.