Figure 3 shows the performance of both the S measure and PMI measure. As the results, all the causal relations are ranked according to each score. This graph plots the precision of the top N relations in the ranked list. It’s obvious that the measure S outperformed the PMI scores. And it further proved that the importance of Co-Occurrence feature referred in Section 2. The best precision and recall of S-E method achieved 89.3% and 83.0%, respectively.