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Impact of A/B testing on Search Engine Optimization (SEO)

Paras Chopra
Founder and Chairman of Wingify.

Update: there is even an official confirmation from Google’s Matt Cutts that split testing does not impact search rankings.

A lot of our potential customers are concerned whether A/B or multivariate testing will have an effect on their search engine rankings. They (obviously) aren’t looking to improve their rankings by using A/B testing, rather their concerns relate to the myth that testing may negatively impact search engine optimization efforts.

Broadly, there mainly two major concerns:

  • Content Cloaking: the act of showing different content to search engine bots and actual human visitors. A/B testing software (such as VWO) swap content on the page using JavaScript, so some users see different content (of variations) and bots see original page only.
  • Duplicate Content: the act of copying content from elsewhere and hosting it on your site. Search engines penalize for such stealing of content because you cannot expect to rank on keywords for the content that isn’t yours. Again, many A/B and multivariate testing software (including VWO) have an option where you can redirect site traffic to different variations of a page which raises this concern.

Why A/B testing is not content cloaking

Cloaking content was all rage back in the early days of search engines (think 1990s). In those days, SEO was all about keyword stuffing. So, smart SEO geeks used to display a page full of keywords when a search engine bot visited to crawl / index the page. While if a user visited the same page, they displayed the default (normal) version. This strategy of keyword stuffing used to work like wonders so naturally search engines started devising clever ways to detect and penalize such cloaking and it may appear that pages where A/B testing is on will also get penalized because it is kind of cloaking.

Good news is that thanks to Google’s PageRank algorithm, keyword stuffing no longer works. So, there is little incentive for search engines to penalize content cloaking. Moreover, unlike yesteryears’ static HTML sites, today’s search engines have come to expect highly dynamic AJAX driven sites. So, they no longer consider swapping content dynamically as cloaking. If you use a multivariate testing software to swap different parts of your page, it is not cloaking! Also, all the major search engines (Google, Yahoo, Bing, etc.) are well versed with concept of A/B split testing and they do many such tests on their own sites every single day. You wouldn’t expect search engines to penalize others for doing the same activity that they themselves do regularly, would you?

Key lesson: Doing A/B testing by dynamically swapping elements on page (using JavaScript) is NOT content cloaking. It is absolutely safe and should not have any negative impact on Search Engine Optimization efforts.

Split URL testing (redirecting traffic to multiple versions) and the issue of content duplication

As I mentioned above, this is another issue that worries many prospective customers. While one approach for split testing is to dynamically swap page elements (such as headlines, images, text, etc.), another approach is to host different variations of page on your website. So, if you want to split test product.html, you will create variation pages and host them as product1.html, product2.html, etc. A split testing software will redirect all traffic coming to product.html to the variation pages. Since product1.html and product2.html will have similar content as product.html, it worries some people that search engines will consider them duplicate content and penalize rankings.

An important point to note here is that search engines only penalize if you steal or host content from a different domain; here all variations pages host on your own site and you OWN that content and are free to do with it whatever you want to. Many dynamic websites (shopping carts, directories, etc.) today host the same content in different formats. Search engines don’t penalize them because that unique content is only found on their domain and no where else. Same is the case with your split testing URLs. You don’t get negatively impacted by it because you haven’t stolen that content — it is all yours!

If you are worried about the SEO ranking of the control page, it is possible to setup a Split URL test in a manner so that you can avoid the issue of duplicate content by using the following on your variation version URL:
Let me explain this with the help of a example below:
A Split URL test is when there are two pages (let’s say http://example.com/A.php and http://example.com/B.php) and when visitors land onhttp://example.com/A.php, half of them are redirected to http://example.com/B.php with some duplicate content on it. In this case, let’s suppose you don’t want B.php to affect your SEO, so what you do is add the following code to B.php i.e. the non-canonical page
<link rel=”canonical”/>
Now Google will index both pages but it will know that http://example.com/A.php is the one to be used for SEO purposes. Here’s the link to the help page from Google’s own website.

Lesson: A/B split testing has absolutely NO negative impact on your SEO efforts!

Rest assured, you can use VWO without worrying about its impact on search engine rankings. If you have a specific SEO and A/B testing related question, let me know in comments below.

UPDATE: Things have changed since this article was written. Please see https://support.google.com/webmasters/answer/7238431/ for Google’s guidelines on A/B testing.

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Shanaz from VWO

Hi, I am Shanaz from the VWO Research Desk.

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