What is the benefit of using a validation dataset?

The use of a validation dataset is essential in the model training process primarily for tuning hyperparameters and preventing overfitting. When you train a machine learning model, you use a training dataset to teach the model about the data. However, if a model is evaluated only on this training dataset, it may perform exceedingly well due to overfitting, meaning it has essentially memorized the training data rather than learning to generalize from it.

A validation dataset serves as a separate partition of the data that the model does not see during training. By evaluating the model's performance on this distinct dataset, you can fine-tune hyperparameters — such as learning rate, regularization strength, and others — to optimize the model's architecture and performance. Adjusting these hyperparameters based on validation performance helps strike a balance between fitting the training data well while maintaining the ability to generalize to unseen data. This process ultimately leads to a more robust model that performs better in real-world applications.

Thus, the benefit of using a validation dataset directly relates to its role in guiding the hyperparameter tuning process and ensuring the model does not simply memorize the training data, thereby mitigating the risk of overfitting.