Examination of Mediation. We will examine mediation in models with structural equations, testing the significance of direct and indirect effects and their equality. Testing will be by the delta method or bootstrapping. While tests involving indirect effects are of primary interest, the investigators will in some cases carry out a priori tests reflecting Mackinnon's recommendations. Mediation will be tested through first showing that X (e.g., ethnic group) is associated with both M (e.g., illness representation) and Y (e.g., treatment decision). Second, a path model is estimated by simultaneously regressing (a) Y on M and X, and (b) M on X. This will be repeated specifying X=illness representation, M=treatment decision, and Y=asthma control. The paths from X to M and from M to Y must each be statistically significant by this criterion, in addition to the significance of the indirect effect. If the path from X to Y drops to zero, full mediation is suggested. Partial mediation is suggested to the extent that X still predicts Y with the mediator(s) simultaneously entered. These first-stage tests also result from the model estimation used for testing the indirect effect. In that model estimation, the investigators use full information methods (e.g., FIML) unless there is clear indication that OLS is adequate. Henderson and Ceci describe delta-test methods for moderation and mediation.