Can A/B Testing Cause An SEO Problem?

Aug 21, 2009 • 8:33 am | comments (7) by twitter Google+ | Filed Under SEO - Search Engine Optimization

A/B testing is the process of setting up two or more styles for a page, for the same piece of content. For example, let's say you had a page where you sold blue widgets and you wanted to try using a blue button versus a red button to buy the widget. What you can do is A/B test the two types of buttons against each other.

How would you accomplish this? Well, you can send 50% of your traffic to and the other 50% to and see which page converts better. But that can lead to duplicate content, i.e. the same URL, with three URLs for the same content. Or would it? Google and some search engines are smart enough to pick up on this. There are other ways to test this using JavaScript (potential cloaking issue?) or CSS or use Google Website Optimizer.

How would you handle it? That is the question asked in a WebmasterWorld thread. Honestly, I am not sure what the "best" method to handle this is. So please join the thread or comment here.

Forum discussion at WebmasterWorld.

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Jill Whalen

08/21/2009 12:59 pm

Blocking the test URLs via robots.txt works well.


08/21/2009 04:08 pm

I'd test however I wanted (whatever works best and is easiest) and generally not let fear of search engine trouble slow me down.


08/21/2009 04:57 pm

no index, follow tag on test page(s).


08/24/2009 06:08 am

Google Website Optimizer works well for A/B testing.


08/24/2009 07:05 am

Once more... What about using link rel="canonical" ? That could help.


08/24/2009 02:14 pm

Since this is an ecommerce site, cookies are presumably used to store session state. I would use "one" page, and set a cookie with the testing information in it. (buybutton=blue) Otherwise you could write each ip address, timestamp, and button used to a testing table, and work backwards to tally things up. "201.32.451.16","08/24/09","red button" no *seo problem* whatsoever.


10/14/2009 01:28 pm

I agree with Jill, set up a split test that works best for you and your business, do not fear of search engine problems from the start. With Logaholic Web Analytics (available from you can set up a URL based or PHP A/B split testing tool in seconds and observe the results in a couple of days.

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