Correction

Theorem 3.1 and Corollary 3.1.1 in the article are false. While Theorem 3.1 correctly states that κ N ð Þ � k, the reverse inequality is not necessarily true (a family of counterexamples can be produced to show this). It should be noted that these statements, while false, are nevertheless tangential to the main emphasis of the paper, which is that cohesion in two-mode networks should be studied without one-mode projections, and that this can be done using both what we call “two-sided” and “onesided” approaches. We have replaced Theorem 3.1 and Corollary 3.1.1 with the following new, correct theorems and accompanying text.