Propension to customer churn in a financial institution: a machine learning approach

This paper examines churn prediction of customers in the banking sector using a unique customer-level dataset from a large Brazilian bank. Our main contribution is in exploring this rich dataset, which contains prior client behavior traits that enable us to document new insights into the main determinants predicting future client churn. We conduct a horserace of many supervised machine learning algorithms under the same cross-validation and evaluation setup, enabling a fair comparison across algorithms. We find that the random forests technique outperforms decision trees, k-nearest neighbors, elastic net, logistic regression, and support vector machines models in several metrics. Our investigation reveals that customers with a stronger relationship with the institution, who have more products and services, who borrow more from the bank, are less likely to close their checking accounts. Using a back-of-the-envelope estimation, we find that our model has the potential to forecast potential losses of up to 10% of the operating result reported by the largest Brazilian banks in 2019, suggesting the model has a significant economic impact. Our results corroborate the importance of investing in cross-selling and upselling strategies focused on their current customers. These strategies can have positive side effects on customer retention.