A study conducted by Stone Temple Consulting has found that Google+ 1’s don’t actually cause higher search-engine rankings.
Their findings contradict what most people in the industry previously believed.
This trail of thought was initiated by Searchmetrics, Moz and others who found correlations between Google+1’s and higher search rankings. However Matt Cutts (head of Google search spam) in a statement claimed that he was looking for the “politest way to debunk the idea that more Google +1s lead to higher Google web rankings.”
This conflict lead to Stone Temple Consulting conducting this study by carrying out an actual measurement of causation between Google+1’s and search ranking. Their key finding was that: "Google Plus Shares did not drive any material rankings changes that we could detect."
The president of Stone Temple Consulting, Eric Enge, details the findings of the study in an article on his website, Direct Measurement of Google Plus Impact on Search Rankings.
Egne stated that the main goals of the study were to see if Google+ would drive discovery, indexing and ranking.
He believed that it is “highly likely that Google+ drove discovery of the content”. Regarding indexing, Enge establish that Google+ shares probably drive indexing too. However with the six test articles (three test pages and three baseline pages), all of the articles did appear in the Google ranking after 10 days.
They found no evidence of Google+ shares driving ranking. When a page had been indexed, search queries were found and the page ranked. However this does not directly mean that Google + shares were not driving ranking.
If you want to find more information, Enge is holding a Google+ hangout on air this Thursday at 4 p.m. A star-studded SEO panel will be with Egne, including Mark Traphagen of Virante, Pete Meyers from Moz, Joshua Berg of Google plus SEO, and Marcus Tober of Searchmetrics.