Rewrite this "We can evaluate a classifier by splitting the data randomly into a training and test data set, using the training set to build the classifier, and using the test set to estimate its accuracy. Finally, we can tune the classifier (e.g., select the number of neighbors in K-NN) by maximizing estimated accuracy via cross-validation." to this "We can tune and evaluate a classifier by splitting the data randomly into a training and test data set. The training set is used to build the classifier and we can tune the classifier (e.g., select the number of neighbors in K-NN) by maximizing estimated accuracy via cross-validation. After we have tuned the model we can use the test set to estimate its accuracy.
Rewrite this "We can evaluate a classifier by splitting the data randomly into a training and test data set, using the training set to build the classifier, and using the test set to estimate its accuracy. Finally, we can tune the classifier (e.g., select the number of neighbors in K-NN) by maximizing estimated accuracy via cross-validation." to this "We can tune and evaluate a classifier by splitting the data randomly into a training and test data set. The training set is used to build the classifier and we can tune the classifier (e.g., select the number of neighbors in K-NN) by maximizing estimated accuracy via cross-validation. After we have tuned the model we can use the test set to estimate its accuracy.