Within the US, among 44 ranking factors examined, social signals account for 7 of the 8 most highly correlated with Google search results, according to a new study from Searchmetrics. Presenting the correlations using Spearman’s rank correlation coefficient, the study determined that Google +1s (0.4) have easily the highest correlation, followed by number of backlinks, Facebook shares, and Facebook total (summary of shares, likes and comments), each at 0.34. Last year’s study, which looked at 21 factors, found social signals occupying 5 of the top 6 spots.
via Social Signals Again Seen Highest Correlating Factors With Google Rankings.