We generate the curves for each system as follows. For Tf-Idf, SingleRank, and ExpandRank, we vary the number of keyphrases, N , predicted by each system. On average, TextRank performs much worse compared to Tf-Idf. This certainly gives more insight into TextRank since it was evaluated on Inspec only for T=33% by<cite> Mihalcea and Tarau (2004)</cite> .