The Secret of Penguin 2.1 is... Readability
Machine learning SEO platform MathSight published some interesting research recently about Google Penguin 2.1 and what's driving decreases or increases in ranking and traffic for websites.
MathSight's research indicated that Penguin uses the Flesch Kincaid and Dale Chall readability tests as part of a combination of metrics to evaluate linking content. “We began to suspect the influence of readability tests shortly after the launch of Penguin 2.1 in October, but have been waiting until we had enough data to rigorously test the hypothesis," said MathSight Systems Architect, Frank Kelly.
"We found that both the Flesch Kincaid Grade Level and Dale Chall readability tests are having an impact, with the number of words per sentence and the ratio of rare and common words all playing a part in site traffic following a Google Penguin update."
According MathSight, Google is favoring Web pages that are well written, well researched and offer sophisticated content. Specifically, the lower the ratio of rare words to the total on offsite linking pages for example, the more detrimental those backlinks are to SEO initiatives.
“Targeting Web pages with poor readability is algorithmically the most efficient way of discounting poor links from Web pages that have content that has not been written professionally and lacks relevant research,” said MathSight Managing Director, Andreas Voniatis. “Instead of only looking at a site’s authority, the SEO should use additional data to evaluate their readability scores before deciding on whether or not they want nurture an editorial relationship with a website for the purposes of link outreach.”