Figure 5
Performance of bivariate models. For each of 377C2 = 70876 possible combinations of the 377 predictor variables, we generated bivariate Cox PH models and evaluated the average concordance index (C) of each model across 20 cross-validation simulations. Colors represent the average concordance of a given model, with respect to the ranking of the two variables contained in a model. The variable rankings are based upon concordance estimates generated for each variable in univariate Cox PH models (i.e., values from Figure 2A), with low ranks assigned to variables of greatest predictive value.