what is cross validation what is the difference between test set and training set what is validation for the k-fold cross validation test what is training data in cross validation what is the test set of the training subsamples how many subsamples for k-fold cross validation what is the definition of testing a model cross validation kfold which subsample is retained in cross validation which subsamples are referred to as training subsamples how is training subsample used in k-fold cross validation what is the difference between test data and training data what is the difference between training and test data what is the difference between testing and test data in cross validation why would cross validation rely on a test set what is the test data for cross validation what is training subsample? which data does cross validation use what is training data used for in cross validation does the validation set include test data?