Accession Number : ADA133848

Title :   An Investigation of Methods for Reducing Sampling Error in Certain IRT (Item Response Theory) Procedures.

Descriptive Note : Technical rept.,

Corporate Author : EDUCATIONAL TESTING SERVICE PRINCETON NJ

Personal Author(s) : Wingersky,Marilyn S ; Lord,Frederic M

PDF Url : ADA133848

Report Date : Aug 1983

Pagination or Media Count : 58

Abstract : The sampling errors of maximum likelihood estimates of item-response theory parameters are studied in the case where both people and item parameters are estimated simultaneously. A check on the validity of the standard error formulas is carried out. The effect of varying sample size, test length, and the shape of the ability distribution is investigated. Finally, the effect of anchor-test length on the standard error of item parameters is studied numerically for the situation, common in equating studies, where two groups of examinees each take a different test form together with the same anchor test. The results encourage the use of rectangular or bimodal ability distributions, also the use of very short anchor tests. (Author)

Descriptors :   *Numerical methods and procedures, *Maximum likelihood estimation, *Error analysis, Mathematical models, Sampling, Errors, Reduction, Parameters, Computations, Analysis of variance, Covariance, Matrices(Mathematics), Tables(Data), Charts

Subject Categories : Statistics and Probability

Distribution Statement : APPROVED FOR PUBLIC RELEASE