The Stability of Four Methods for Estimating Item Bias.

The stability of bias estimates from J. Schueneman's chi-square method, the transformed Delta method, Rasch's one-parameter residual analysis, and the Mantel-Haenszel procedure, were compared across small and large samples for a data set of 30,000 cases. Bias values for 30 samples were estimated for each method, and means and variances of item bias were computed across all the samples, for comparisons contrasting sample size, sex, and race. The point estimates of item bias, based on 30 replications for each method, were also correlated across random samples, and classification techniques compared the results for agreement. The results showed that none of the methods consistently flagged more or fewer items as biased, though at the larger sample sizes the Mantel-Haenszel and Rasch methods were particularly sensitive at detecting item bias and in high agreement. Reliabilities of the Modified Delta method were generally lower than the others, as were the correlations between Modified Delta and the other indices. The results showed that not until the number of cases in each comparison group reached 1,000 did the reliabilities for any technique approach 0.80. (Contains 5 tables and 22 references. (Author/SLD)