Can you explain how overfitting occurs in Machine Learning models and share your strategies to prevent it?

How To Approach: Associate

  1. Talk about real-life experience with overfitting.
  2. Explain how overfitting was identified.
  3. Detail steps taken to address the issue.
  4. Discuss impact on overall model performance.

Sample Response: Associate

In my current role as a Data Analyst, I have encountered the issue of overfitting multiple times. For instance, in a project involving churn prediction for our company's client base, our initial model had an excellent accuracy rate with the training data set but performed poorly on the validation set. This discrepancy alerted us to a possible overfitting scenario.

To attend to this problem, we first simplified our model by performing feature selection. We carefully scrutinized the input factors and eliminated those that were less important or causing noise. We then implemented L1 regularization, adding a penalty term to our loss function, which helped further prevent potential overfitting by reducing the magnitude of the coefficients.

These adjustments significantly improved our model's performance on validation data, ensuring our predictions remained consistent and reliable, irrespective of the data the model was exposed to. It also underscored the importance of model robustness and the careful consideration that should be given to tackling overfitting during the model development stage.