Words were separated into groupings based on how many language families appeared to be cognate for the word. Among the 188 words, cognate groups ranged from 1 (no cognates) to 7 (all languages cognate) with a mean of 2.3 ± 1.1. The distribution of cognate class size was positively skewed − many more small groups than large ones − as predicted by their hypothesis of variant decay rates. Words were then grouped by their generalized worldwide frequency of use, part of speech, and previously estimated rate of replacement. Cognate class size was positively correlated with estimated replacement rate (r=0.43, p<0.001). Generalized frequency combined with part of speech was also a strong predictor of class size (r=0.48, p<0.001). Pagel "et al." conclude "This result suggests that, consistent with their short estimated half-lives, infrequently used words typically do not exist long enough to be deeply ancestral, but that above the threshold frequency words gain greater stability, which then translates into larger cognate class sizes."