Stracciafabrizio’s Weblog

There’s so many reasons why PageRank shouldn’t be a primary metric for SEO:

• Infrequently updated – Google updates the PR scores in the toolbar 2-4X each year on an unpredictable and unpublished schedule. The PageRank score you see today could be dramatically different than the PageRank Google’s using in ranking/crawling calculations.
• 1 of 200+ ranking signals – Google’s representatives have continually repeated that PageRank is just one of “more than two hundred” signals the engine applies to the rankings equation.
• Applies to pages, not sites – The PR score is based on individual URLs, not domains. Technically, there’s no such thing as a “PR 5″ website, just a website with a homepage URL that has displays “5″ in the toolbar.
• Imprecise – PageRank is a logarithmic score when fitted to a 0-10 value in the toolbar. We’ve estimated the log base around 8-10, meaning that a PR5 URL has 8-10X more PageRank than a PR4. Yet, there’s no granularity between values. One PR4 page might have 5 times more PageRank than another PR4 page, but the Google score won’t tell you until the log base threshold has crossed the next value marker.
• Intentionally Inaccurate - Google has been using toolbar PageRank to visually penalize pages and sites for buying/selling links for many years, but they readily admit they use this filter intermitently so as not to tip off spammers. Thus, we’re never sure when looking at PageRank whether a page/site has or hasn’t had its PageRank reduced and whether that does or doesn’t impact rankings (or the value passed by the non-manipulative links). Read the rest of this entry »