Hello everyone I am using nested resampling in caret (5-fold outer and bootstrap inner resampling) and by default, it shows the "Accuracy" metric. How can I use it for the ROC/AUC metric? My code is: d=readARFF("apns.arff") index <- createDataPartition(d$isKilled , p = .70,list = FALSE) tr <- d[index, ] ts <- d[-index, ] boot <- trainControl(method = "boot", number=100, search="random", classProbs = TRUE, summaryFunction = twoClassSummary) outer_folds <- createFolds(d$isKilled, k = 5) boot <- trainControl(method = "boot", number=10) CV1 <- lapply(outer_folds, function(index){ tr <- d[-index, ] ts <- d[index,] cart1 <-train(isKilled ~ ., data = tr, method = "rpart", tuneLength = 20, metric = "Accuracy", preProc = c("center", "scale", "nzv"), trControl = boot) postResample(predict(cart1, ts), ts$isKilled) }) sapply(CV1, function(x) x[3]) -> CV_MAE1 CV_MAE1 [[alternative HTML version deleted]]