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How to know if any website is using Google Website optimizer for A/B testing? By viewing a source code. For what to look into view source which confirms that site is using Google Website optimizer

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Look for the _utmx cookie for the site in question.

From Google

You can use Google Analytics with Google Website Optimizer (GWO), which is a tool that helps determine the most effective design for your site. When a website optimizer script executes on your page, a _utmx cookie is written to the browser and its value is sent to Google Analytics. See the Website Optimizer Help Center for more information.

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NO _utmx in source code of website – metal-gear-solid Apr 24 '12 at 2:40
And only these cookies are showing i.imgur.com/arEii.jpg no _utmx – metal-gear-solid Apr 24 '12 at 2:43
It's possible they are using a different testing system like phpabtest or any of the many others. – bikedorkseattle Apr 24 '12 at 7:20

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