31 Must-Read SEO Experiments and Test Findings

31 Must-Read SEO Experiments and Test Findings

Testing And Experimenting Is (Or At Least Should Be) The Backbone Of Any SEO Strategy.

Most professional SEO companies and experts routinely conduct formal and informal SEO experiments, some of which are generously posted online for education and calibration purposes. At SEO.com, we encourage our employees to build and monetize personal websites when they’re not at work, as an opportunity to innovate, test, and take risks that we can’t with our client campaigns at work.

Now I’m sure this post will attract a lot of scientific method purists that insist that 99% of these tests are invalid because they were conducted in uncontrolled environments, or didn’t account for all possible external variables, etc.  And they would be absolutely right, but I respond with a paragraph from John Quarto-von Tivadar’s MarketingLand post, mainly because I couldn’t have said it better myself:

Ever hear the adage, “Anything worth doing is worth doing wrong”? It’s a great way to think about testing and improvement of any kind, because it deals with the fact that the first step toward improvement always “feels” the hardest. It speaks to the moment when you’re most susceptible to false objections like “It’s too complex!” or “That’s inefficient!”

In my opinion, these studies are incredibly valuable and interesting, and should be read and understood with a conscious understanding that they are not examples of perfect science. They’re “helpful” observations, that in most cases increase our understanding of the science of SEO and its best practices, even if they’re not scientifically sound.






  • First-Link Anchor Text Attribution
    Rand confirms that only the first link in the source code, pointing to any other specific page on the web, actually passes any anchor text attribution. So don’t think you’re helping your home page by linking with “cheap gifts” in your footer, after you’ve linked to your home page 3 times already.
  • First Link Counted Rebunked
    SEO Scientist Rebunks SEOmoz’s tests on first link anchor text attribution.


This list is certainly not complete, so please be as generous in the comments as these professionals were kind enough to post their findings for our benefit in the first place, by adding any tests you’ve conducted, or that you feel will complete this list (to date).

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  1. Giuseppe Pastore says

    Very interesting post!

    I like testing and I think we should keep trying to get a deeper understanding of search engines work. I don’t know if it’s a good fit for this list, but, for example, this year I tested how many words Google indexes as Tag title and discovered that after the 12th, the rest of a Title is indexed as text. Moreover, the distance between “Title text” and “body text” can be counted as words using AROUND() and depends on HTML tags between them…(more here: http://en.posizionamentozen.com/blog/reverse-engineering-tag-title-my-seo-test/).
    Anyway, from my few tests I’ve learned something very important (I guess): one should never stop doing their own tests… it’s the only way you have to find something new! 😉

    Thanks for the list Clay, I’ve read some of this posts but I see I need to check some of them (and thanks again for the mention in “Testing the 1st Link Priority Rule”) :)


    • Claye Stokes says

      @Guiseppe I’m glad you found it worthwhile! Thanks for sharing your example, that’s actually a fascinating example, so thanks for adding it to the list.

  2. Joe says

    Thank you for this excellent info that will be a major help to me and any other online marketing newbie trying to bring much needed traffic. This page is offically bookmarked!

  3. Ignite Visibility says

    This is a cool post. It covers so much random SEO information. These are the little things that clients ask about. I really like the experiments that were done.

  4. Matt Coffy says

    Great list to read, Claye. SEO really is about experimenting and testing. Being open to take such risks is essential to the success of your efforts. Thanks for the post, I’ll be sure to check most (if not all) soon.

  5. Claye Stokes says

    @Laura, uh, yeah – seriously great post! Thanks for suggesting it. Your link just made my top 3 (of this entire list) for your research on approaching title tags in the same way we approach ad headlines.

    Everyone should read that article and pay attention to the results of this hypothesis:

    By reflecting the campaign offer in the SEO title tag results we will: increase SEO traffic and decrease campaign attributable PPC costs, without negatively impacting total forecasted search sales.

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