Can Any Single Metric Predict the Rankings?
Boy, that sure would be nice... We've looked in the past at the quality of metrics like PageRank, Yahoo! Site Explorer's Link Counts, Alexa Rank, etc. The short answer is that they're barely better than random guessing. Google's PageRank score was (around February of 2009) approximately 16% better than random guessing for predicting ranking page (N+10 aka ranking page 1 vs. page 2) and less than 5% better than random guessing for predicting ranking position (N+1 aka ranking position 1 vs position 2). The chart below shows correlations for a number of popular SEO metrics: