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Table 4 11-point precision diagram. This example shows a query that is submitted to two different IR systems (IR1 and IR2), which are based on the same collection of 20 documents. Both IR1 and IR2 rank all 20 documents, of which 10 are relevant. However, IR1 ranks the relevant documents higher on average than does IR2. The mean average precision for IR1 = 0.79 and for IR2 = 0.40. The recall and precision curves for IR1 and IR2 are shown in figure 2.

From: A tutorial on information retrieval: basic terms and concepts

Ranking by IR1 Ranking by IR2
Ranking Doc Relevant Recall Precision Ranking Doc Relevant Recall Precision
1 d 1 yes 0.10 1.00 1 d1 no 0.00 0.00
2 d 2 yes 0.20 1.00 2 d2 no 0.00 0.00
3 d 3 yes 0.30 1.00 3 d3 no 0.00 0.00
4 d4 no 0.30 0.75 4 d4 no 0.00 0.00
5 d 5 yes 0.40 0.80 5 d5 no 0.00 0.00
6 d6 no 0.40 0.67 6 d 6 yes 0.10 0.17
7 d 7 yes 0.50 0.71 7 d 7 yes 0.20 0.29
8 d8 no 0.50 0.63 8 d 8 yes 0.30 0.38
9 d 9 yes 0.60 0.67 9 d9 no 0.30 0.33
10 d10 no .060 0.60 10 d 10 yes 0.40 0.40
11 d 11 yes 0.70 0.64 11 d11 no 0.40 0.36
12 d 12 yes 0.80 0.67 12 d 12 yes 0.50 0.42
13 d 13 yes 0.90 0.69 13 d13 no 0.50 0.38
14 d14 no 0.90 0.64 14 d 14 yes 0.60 0.43
15 d 15 yes 1.00 0.67 15 d15 no 0.60 0.40
16 d16 no 1.00 0.63 16 d 16 yes 0.70 0.44
17 d17 no 1.00 0.59 17 d 17 yes 0.80 0.47
18 d18 no 1.00 0.56 18 d 18 yes 0.90 0.50
19 d19 no 1.00 0.52 19 d19 no 0.90 0.47
20 d20 no 1.00 0.50 20 d 20 yes 1.00 0.50