Description:
<jats:title>Abstract</jats:title><jats:p>Testing programs are often interested in using a student growth measure. This article presents analytic derivations of the accuracy of common student growth measures on both the raw scale of the test and the percentile rank scale in terms of the proportional reduction in mean squared error and the squared correlation between the estimator and target. The study contrasts the accuracy of the growth measures against that of current status measures—current test scores and their percentile ranks. Key findings include the extent that status measures are more accurate than any of the growth measures and that alternative methods to estimate growth could be more accurate than the currently used methods. Our findings highlight the importance for evaluating the statistical properties of growth measures along with other concerns for states that are debating the reporting of growth. Our results also point out that assessing the accuracy of growth measures requires the specification of quantities of interest in terms of latent achievement rather than observed test scores, which is common practice for developing status measures but essentially never done by testing programs for growth measures.</jats:p>