Abstract
As part of their review of the estimation and use of “change” scores, Cronbach and Furby and O’Connor recommended procedures designed to increase the precision of estimators of individual true gain. The intent was to develop estimators which yielded smaller mean squares of (D ∞ –D ∞), where (D ∞ is true gain. The present study was designed to examine the effects of three parameters upon this mean square, where the estimator of D ∞ employed was one originally proposed by F. M. Lord. The three parameters studied were the correlation between the true score on the initial test and true gain (r ξγ), the reliability of the initial test r xx sample size. Of principal interest were the effects of the initial test true score-true gain correlation. The ANOVA results indicated that r ξγ has a pronounced effect upon the precision of D ∞ but this effect is moderated by r XX general, higher values of r ξγ yielded smaller errors in D D ∞. These results were considered in the discussion of the extended estimator proposed by Cronbach and Furby.
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