Controlled Experimentation + Correlation Data Gives Solid Evidence

I am always excited to hear that our internal testing using controlled experimentation matches up with that of those doing correlation studies, like the great work coming out of SEOMoz. Most recently, Rand Fishkin posted a great piece on correlations between numerous ranking factors and outcomes in both Google and Bing.

One of the more “surprising” pieces of data revealed in this correlation study was the relationship between the .org extension vs. .net/com/gov/etc. It seems that in both Bing and Google, there is a slight bias towards the .org TLD.

Interestingly, back in 2008 before SEOMoz had built such a great data set to perform correlation studies like this, we created a controlled experiment to look at potential Top Level Domain Analysis. We generated hundreds of sites and subdomains with gibberish content, indexed them using Google Webmaster tools, and looked for patterns on which ones ranked better based on domain extension alone. The resulting piece was named Google Showing Bias Towards Org TLDs.

The bigger question is what is going on in these examples. Looking at the correlation data, I would be quick to say that there is no overt bias, and that .orgs probably gather more links than other domains: the right mix of being non-commercial but not unmarketed. However, the controlled experiment showed bias even when there were no links present at all. Of course, this only looks at Google and not Bing, but there may be a hint of commercial intent weighed into the rankings metrics. If .org is seen as a non-commercial indicator, it could increase the likelihood that it would rank well in SERPs where Google is looking for non-commercial results. Unfortunately, it will be difficult to determine the exact answer to this question.

So, Matt, is there a commercial intent factor that we must consider? Or is it just random happenstance?

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  1. PPC Blog
    Jun 9, 2010

    If I was cynical I would suggest that Google might think a .org site might have bettre content and be more trustworthy because it’s a non profit entity. But ofcourse I’m only guessing.

  2. Michael Martinez
    Jul 1, 2010

    I’ll get interested when the “correlations” approach 1 (anything less than .95 is pretty much a NON-correlation).

  3. admin
    Jul 5, 2010

    Less than .95 what? Confidence? If you think we can discover a 1:1 direct relationship between a single ranking factor and the search results, you are insane. We know google has hundreds of factors, from which we can deduce that not a single factor will have a direct 1:1 relationship (unless it is the only factor that matters).

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