Evaluation Metrics in Information Retrieval(信息检索中的评价指标)

1. Confusion Matrix(混淆矩阵)

	Relevant	Nonrelevant
Retrieved	True Positive	False Positive
Not Retrieved	False Negative	True Negative

2. Precision and Recall

Precision = TP/(TP+FP)，即被检索出的文档中真正相关的文档所占的比例。
Recall = TP/(TP+FN)，即真正相关的文档中被成功召回（检索）的文档所占的比例。

下图解释较为形象：

3. F measure

We normally use a balanced F1 measure with β=1.

4. Rank-Based Measures

Slides: Stanford CS276 Ranked-Based Measures

• Precision@K
• Mean Average Precision (MAP)
• Mean Reciprocal Rank (MRR)
• Normalized Discounted Cumulative Gain (NDCG)