Is there proof that social signals from google+ or FaceBook are a ranking factor?

Selected answers from the Dumb SEO Questions Facebook & G+ community.

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  Vangelis Kovaios: Hi all,
  
  After reading several articles regarding G+ correlation with higher rankings, i am still not convinced that google search algorithm evaluates social signals to adjust the SERPs display in terms of rankings.
  
  In particular, according to the latest moz & searchmetrics surveys for ranking factors, they found that the correlation of +1s with rankings is so high that surpasses the importance of the number of backlinks...
  
  Do you have any irrefutable proof that social signals from g+ (or even fb) are indeed a measurable ranking factor?
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  Brent Wildman: You said it in your first sentence, "correlation." I haven't really seen anyone say that the more +1's you have, the higher you will rank. Of course if you have really good content that causes you to rank higher, you will have a large number of +1's and shares.
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  Andrei Gherghel: You may take a look at http://searchengineland.com/study-shows-no-clear-evidence-that-google-plus-drives-ranking-171789 to find out more.
  Cheers
• 
  Vangelis Kovaios: Thanks for the citation +Andrei Gherghel .... it's a proper academic study
• 
  Vangelis Kovaios: Many thanks for your answer +Brent Wildman . Indeed as +Eric Enge ; concluded there is no clear evidence (yet)
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  Simon Fryer: +Brent Wildman is bang on the money here.
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  Frank Rodríguez: +Vangelis Kovaios ;Refutable? Nothing with Internet or the Google algorithm is. Do what the scientist do... try it yourself & monitor the results...like everything you do online. For me it works, top content which is relevant, in demand & of value & people will +1s & distribute. Plus use the "follow link" on Gplus. Cheers & good luck with your experimenting.
• 
  Mike Stetzer: Correlation does not equal causation.
  
  Big brands tend to have larger social followings and ultimately, more +1's. Coincidentally, bigger brands tend to have more "authority" and ultimately rank better. ;