Note on Ely's "Effects of various methods upon test reliability."

Abstract

Ely gives 24 correlations for each of the four methods of item analysis he investigated. An examination of the median coefficients of the 24 reported for each method shows them to be: D, .876; r , .878; Phi, .864; and %, .864. The greatest difference here is .014. Although this difference is statistically significant, it is more than doubtful that it is significant in any practical sense. The value of Ely's article is not in its demonstration of statistical superiority of the three methods over the per cent method, but in finding that the simple and easily obtained per cent difference will be equally as effective in similar practical situations as the more difficult and harder to obtain D, r , and Phi methods. (PsycInfo Database Record (c) 2025 APA, all rights reserved)