Evaluating a classifier a How well will the classifier we learned perform a novel data? a We can estimate the performance(e.g, accuracy, sensitivity) of the classifier using a test data set Performance on the training data is not a good indicator of performance on future data Test set: independent instances that have not been used in any way to create the classifier Assumption both training data and test data representative samples of the underlying problemEvaluating a classifier ◼ How well will the classifier we learned perform a novel data? ◼ We can estimate the performance (e.g., accuracy, sensitivity) of the classifier using a test data set ◼ Performance on the training data is not a good indicator of performance on future data ◼ Test set: independent instances that have not been used in any way to create the classifier ◼ Assumption: both training data and test data representative samples of the underlying problem