Offline vs Online Evaluation

Offline metrics (Accuracy, F1, RMSE) are necessary but insufficient for measuring business impact.

Home / Guides / Offline vs Online Evaluation

The Offline Trap

A recommendation model with a higher offline NDCG might perform worse in production if it optimizes for engagement on clickbait, actively harming long-term user retention.

A/B Testing (Online)

The only true measure of a model is an online A/B test measuring the primary business KPI (revenue, conversion rate, time-on-site). Always reserve a holdout group.

Internal Resources