If we use cross validation in trainControl function, still do we need to perform the prediction on test set or training data in train function is sufficient?

I split the data in training and testing, used k fold cross validation in trainControl and prediction in train function. Is it OK?


1 Answer 1


You'll always use your unseen test data to evaluate your model in order to be fair and reduce bias in your results.

  • $\begingroup$ OK but when we use k fold cv, the test data is always separated from the train data. So still we need to perform the prediction on test data such as, rmse(ts$output variable, predict) $\endgroup$
    – AAA
    Commented Jan 21, 2020 at 11:08
  • $\begingroup$ You have two splits: train and test. In the train, when you perform some kind of cross-validation, you split your training set into training and validation sets. But, test is outside of these splits. You have train and validation sets throughout your hyper-parameter optimization. Then, after finalizing the model, you'll use the whole training set and predict on the test set. $\endgroup$
    – gunes
    Commented Jan 21, 2020 at 12:47
  • $\begingroup$ Thanks a lot gunes $\endgroup$
    – AAA
    Commented Jan 22, 2020 at 9:26

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