In Retrieval System there are 3 types of metrices

1. Predictive Metrics: It shows how much of the items are really accurate / relevant
   1. For graded list (Pointwise Ranking)
      2. Mean Absolute Error (MAE)
      3. Mean Squared Error (MSE)
      4. Root Mean Squared Error (RMSE)
   2. For binary list (for each item, we have relevant or not)
      1. Precision@K
      2. Recall@K
      3. F-Beta@K
2. Ranking Metrics: It shows how well the system could sort the retrieved items
   1. Mean Reciprocal Rank (MRR)
   2. NDCG
3. Behavioral Metrics: It shows different specific properties of the model, like diversity, novelty
4. Business Metrics: It shows the business profit or evaluation like user clicks, user buy, user retention, user watched and so on.

References