We illustrated the performance of our proposed sampling design using **data** from the National Wilms' Tumor study (NWTS) (D'angio et al., 1989;Green et al., 1998). The **data** consist of N = 3915 observations. The variables available for all the individuals include histology evaluated by institution (favorable vs. unfavorable (instit)), histology evaluated by central lab (favorable vs. unfavorable (histol)), stage of disease (I-IV (stage)), age at diagnosis (age), diameter of tumor (tumdiam), study (3 vs. 4 (study)) and indicator of relapse (relapse). We assumed central lab histology was only available at phase 2 and was the variable of interest. All the other variables were assumed to be available for the whole cohort. Following (Kulich and Lin, 2004;Breslow et al., 2009b;Rivera and Lumley, 2016), a similar outcome model was fitted as P r(relapse|histol,age 1 ,age 2 ,stage 1 ,tumdiam) = expit(β 0 + β 1 histol + β 2 age 1 + β 3 age 2 + β 4 stage 1 + β 5 tumdiam + β 6 tumdiam × stage 1 ),