AI engineering glossary · Evaluation metrics
What is NDCG (normalised discounted cumulative gain)?
Normalised discounted cumulative gain (also called NDCG, nDCG): The discounted cumulative gain divided by the best score achievable with a perfect ordering of the same items, giving a value between 0 and 1 that can be averaged across queries. It is the standard metric for graded-relevance search and recommendation ranking.
Normalised discounted cumulative gain: an example
A list with grades [2, 3, 0] has DCG about 3.89 while the ideal order [3, 2, 0] has 4.26, so NDCG = 0.91.
Related terms
More Evaluation metrics terms
- Normalised mutual information
- Normalised RMSE
- Operating point
- Partial AUC
- pass@k
- Perplexity
- Pinball loss
- Platt scaling
Where you learn it
Normalised discounted cumulative gain is part of the AI Engineering Program, which teaches it with notes, a hands-on lab and an exam. The first lesson is free.