Abstract
In order to facilitate comparisons across follow-up studies that have used different measures of effect size, we provide a table of effect size equivalencies for the three most common measures: ROC area (AUC), Cohen's d, and r. We outline why AUC is the preferred measure of predictive or diagnostic accuracy in forensic psychology or psychiatry, and we urge researchers and practitioners to use numbers rather than verbal labels to characterize effect sizes.
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Strictly speaking, d values pertain only to variables scored on an interval scale. When the nondichotomous variable is ordinally scaled, r or AUC should be used. Nevertheless, the values in Table 1 allow one to compare the relative magnitudes across studies that have reported any of the three effect size measures.
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Rice, M.E., Harris, G.T. Comparing Effect Sizes in Follow-Up Studies: ROC Area, Cohen's d, and r. Law Hum Behav 29, 615–620 (2005). https://doi.org/10.1007/s10979-005-6832-7
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DOI: https://doi.org/10.1007/s10979-005-6832-7