randomness • Repeating the process – Illustrates variability in prediction accuracy – Can indicate whether differences in models are consistent across splits • I usually repeat the training / testing split • Folding (5-fold, 10-fold, k-fold, LOOCV) partitions data into equally-sized subsets – One fold is used as testing, with remaining folds as training – Repeated for each fold as testing • I don’t do this as often Refinements and variations