title: Comment on "Cooperation in an evolutionary prisoner's dilemma on networks with degree-degree correlations".
abstract: In a recent publication [Phys. Rev. E 80, 026105 (2009)10.1103/PhysRevE.80.026105], Devlin and Treloar characterized the effects of heterogeneity and degree-degree correlation on cooperation in correlated networks by using standardized variance and a correlated extension of standardized variance. We show that some statements made by them are problematic by considering the relation between these two types of standardized variance with Pearson correlation coefficient.
authors.forename: Yun
authors.initials: Y
authors.lastname: Zhu
authors.forename: Yuting
authors.initials: Y
authors.lastname: Li
authors.forename: Junzhong
authors.initials: J
authors.lastname: Yang