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Model evaluation is essential to assess prediction accuracy from "summary" of Introduction to Machine Learning with Python by Andreas C. Müller,Sarah Guido
Model evaluation is essential to assess prediction accuracy. It allows us to estimate how well our model will generalize to new, unseen data. Without proper evaluation, we have no way of knowing whether our model is performing well or if it is just memorizing the training data. There are several methods for evaluating a model, each with its strengths and weaknesses. One common approach is to split the data into training and test sets. The model is trained on the training set and then evaluated on the test set. This gives us a good estimate of how well the model will perform on new data. However, this approach can lead to overfitting if the test set is used too many times for model evaluation. Another method is cross-validation, where the data is split into k folds and the model is trained and evaluated k times. This gives us a more reliable estimate of how well the model will generalize to new data. Cross-validation is especially useful when we have a limited amount of data, as it allows us to make the most of the data we have. When evaluating a model, it is important to choose an appropriate metric to measure its performance. The choice of metric will depend on the specific problem we are trying to solve. For classification problems, common metrics include accuracy, precision, recall, and F1 score. For regression problems, common metrics include mean squared error, mean absolute error, and R-squared. In addition to choosing the right evaluation metric, it is also important to consider the context of the problem. For example, in a medical setting, a false negative (missing a diagnosis) may be more costly than a false positive (incorrectly diagnosing a healthy patient). In this case, we would want to optimize our model to minimize false negatives, even if it means increasing false positives.- Model evaluation is a critical step in the machine learning process. It allows us to determine how well our model is performing and whether it is ready to be deployed in a real-world setting. By carefully evaluating our models and choosing the right metrics, we can ensure that our predictions are accurate and reliable.