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Can cross-validation be used for Hyperparameter tuning?
The k-fold cross-validation procedure is used to estimate the performance of machine learning models when making predictions on data not used during training. This procedure can be used both when optimizing the hyperparameters of a model on a dataset, and when comparing and selecting a model for the dataset.
Is cross-validation used for training?
Cross-Validation is an essential tool in the Data Scientist toolbox. The training set is used to train the model, and the validation/test set is used to validate it on data it has never seen before. The classic approach is to do a simple 80%-20% split, sometimes with different values like 70%-30% or 90%-10%.
How does cross validation work in hyperparameter tuning?
The data that is remaining, i.e. everything apart from the test set, is split into K number of folds (subsets). The Cross-Validation then iterates through the folds and at each iteration uses one of the K folds as the validation set while using all remaining folds as the training set.
How are test sets used to choose hyperparameters?
The test set is normally a part of the data that you want to use to check how good the final, trained model will perform on data it has never seen before. If you use this data to choose hyperparameters, you actually give the model a chance to “see” the test data and to develop a bias towards this test data.
Is using both training and test sets for hyperparameter tuning overfitting?
The remedy is to use three separate datasets: a training set for training, a validation set for hyperparameter tuning, and a test set for estimating the final performance. Or, use nested cross validation, which will give better estimates, and is necessary if there isn’t enough data. Yes, you are overfitting.
Which is the best form of cross validation?
This particular form of cross-validation is a two-fold cross-validation —that is, one in which we have split the data into two sets and used each in turn as a validation set. We could expand on this idea to use even more trials, and more folds in the data—for example, here is a visual depiction of five-fold cross-validation:
https://www.youtube.com/watch?v=jY2v4q3TPbs