An article on Moz blew up the SEO community last week when it outlined the high correlation between Google +1s and higher search rankings.

Author Cyrus Shepard claims that, besides Moz’s own Page Authority statistic, a URL’s number of Google +1s is more highly correlated with search rankings than any other factor. Searchmetrics, another SEO website, found the exact same thing in a similar study using different methods.

That’s all well and good, but the real question is whether the higher search results are driven by +1s or are merely coincidentally mirroring them.

Shepard acknowledges this question, but says that his study shows that it is not merely correlation, but in fact causation between Google+ posts and search rankings.

He notes three big reasons why he sees this correlation:

  1. Posts are crawled and indexed almost immediately
  2. Google+ posts pass link equity
  3. Google+ is optimized for semantic relevance

In looking at his claims, let’s start off by saying that Google has already flatly denied the thesis of Shepard’s work. Google engineer Matt Cutts said this week on a Hacker news forum post about the article:

“Just trying to decide the politest way to debunk the idea that more Google +1s lead to higher Google web rankings. Let’s start with correlation != causation:

But it would probably be better to point to this 2011 post (also from SEOMoz/Moz) from two years ago in which a similar claim was made about Facebook shares:… . From that blog post from two years ago: “One of the most interesting findings from our 2011 Ranking Factors analysis was the high correlation between Facebook shares and Google US search position.”

This all came to a head at the SMX Advanced search conference in 2011 where Rand Fishkin presented his claims. I did a polite debunk of the idea that Google used Facebook shares in our web ranking at the conference, leading to this section in the 2011 blog post: “Rand pointed out that Google does have some access to Facebook data overall and set up a small-scale test to determine if Google would index content that was solely shared on Facebook. To date, that page has not been indexed, despite having quite a few shares (64 according to the OpenGraph).”

If you make compelling content, people will link to it, like it, share it on Facebook, +1 it, etc. But that doesn’t mean that Google is using those signals in our ranking.

Rather than chasing +1s of content, your time is much better spent making great content.”

So, with that out of the way, let’s take a look at each of Shepard’s points.

1. Posts are crawled and indexed almost immediately

While I haven’t been able to find any hard evidence to confirm this claim, but it certainly falls within reason. Having a strong Google+ profile is absolutely a good way to be indexed by Google’s algorithm. Maintaining and updating your G+ page is extremely important for social media and seo, especially if this claim that posts are indexed immediately is true

2. Google+ posts pass link equity

Shepard claims that because all links from Google+ are followed, they pass on link equity. Dave Davies at Search Engine Watch, who called this claim unlikely, says,

“[Shepard] claims that shared links pass link weight simply because they’re not nofollowed (whereas other links are). Now, this brings up an interesting question: Does the fact that Google nofollows some links necessarily indicate that they pass weight to the others?

One could ask, ‘Why nofollow some if you aren’t going to pass weight to any?’ More likely than passing link weight from the easily abused environment that would breed goes back to point one – they will crawl the content that is shared (i.e., followed) and not crawl additional links, thus seriously restricting the benefits of comment spamming on stronger profiles.

I can’t say the conclusion that the links are nofollowed just to pass crawlers and not link juice is heavily tested or based on more than an understanding of what Google’s trying to accomplish and the pitfalls if they started passing link weight through Google+, but I will assert that it’s far more likely than Google setting themselves up to be a link spam property.”

Google is unlikely to let its own social networks be abused for search rankings, which makes Shepard’s claim dubious. The most likely scenario is that Google is following these links to index posts on its own site, not to pass link juice onto anyone posting on G+.

3. Google+ is optimized for semantic relevance

Google does rank its own site for relevance. That much is undoubtedly true. What we don’t know, and the crux of this point, is whether Google assigns that relevance to the post itself or the destination URL. Matt Cutts hasn’t answered that question, and without his input I doubt the author can make this claim with any certainty.


Google+ plays a role in SEO. What that role is exactly is unclear to everyone outside (and probably most people within) the Google offices. Without hard evidence, we need to treat the claims of Moz as merely correlation, without proven causation.

As Cutts said himself, you’re wasting your time if all you try to do is get +1s. Great content will be shared, and that should be your focus.

Jackson on Google+


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