From the original article: "In Google’s post-Panda/Penguin search algorithm, social shares are now more important than keywords. This is one of the takeaways from a comprehensive study of UK Google ranking factors by search analytics firm Searchmetrics.
The study was based on a data-set of 10,000 selected top-keywords, 300,000 websites and millions of links, shares and tweets collected in February and March of 2012. Searchmetrics aggregated billions of data points looking for the answer to one basic the question: “Which factors are relevant for a good ranking in Google search results”?"
Via Antonino Militello, Robin Good