On the measures of implicit bias, all three IATs showed statistically significant effects (P < .001), with stronger associations of negative attributes (e.g., bad and uncooperative) to blacks than to whites. Figure 2 displays a graph of the magnitude of physicians’ bias on the 4 explicit measures (top half) and 3 implicit measures (bottom half). Because measures of explicit bias (5- and 10-point scales) and implicit bias (reaction time scores ranging from −1.01 to +1.35) were on different scales, the magnitude of physicians’ bias across the seven measures could only be directly compared by converting them all to the same metric—Cohen’s effect size d. Cohen’s d is conceptually defined as the magnitude of an effect independent of sample size (see conversion formula at the bottom of Fig. 2) and is widely used in empirical research and meta-analysis in the behavioral sciences. Cohen’s d values range in size from small (0.20), to medium (0.50), and large (0.80).25 As shown in Figure 2, none of the explicit effects approached the cutoff for a small effect. In contrast, all of the implicit effects were medium or large in magnitude.
