Google Optimizer is a free product from Google that allows you to run A/B and multivariate tests. All you need is a Google account and the desire to make more sales. In this article I will review Google Website Optimizer, the setup, the effects on search engine rankings and touch on the topic of cloaking (since Website Optimizer is in part a cloaker).
To get the most out of this article, you need to be familiar with the following terms: A/B Test and Multivariate Test.
An A/B Test (also called a split test) is a test in which two versions of the page are tested against one another. The test involves the original page and a variation of the page. The variation can contain ANY changes. A/B tests are perfect for beginners, for quick tests and for websites with low traffic. You can get data very quickly in comparison to a multivariate test.
A Multivariate Test is a test in which page variables such as headlines, calls to action, paragraphs, buttons, etc are tested against each other. Google allows up to 1000 multivariable tests at once. For example, if you have six headlines and want to test three variations for each, you can set up: 6 x 6 x 6 = 216 tests. Multivariate tests require a long time to produce data, but are much more effective than A/B.
The Biggest Question of All – Does Google Website Optimizer Affect Search Engine Rankings?
If you do search engine optimization, then obviously this is the biggest question. Why? Because Google Website Optimizer (let's call it GWO for short) serves different pages to different users (up to 1000 variations). How does the Google bot behave towards it? What if it follows a link and gets a different page all the time? Will I lose rankings? Those are the questions you should be asking.
Here’s a clear answer by Tom Leung, Business Product Manager of Google Website Optimizer team in an interview with conversion guru Brian Eisenberg:
Bryan Eisenberg: "Any time you do, any kind of multivariate, A/B testing, what will the Google search engine think of the page?"
Tom Leung: "Using the website optimizer in and of itself will not affect your Google search engine rankings, because the original content will still be there and be indexed as if you weren’t testing. However, if you use the test and if you find ways to give a better customer experience and then you implement those changes, then you should have every reason to believe that it will be reflected in a positive way in your rankings. Using the tool in and of itself won’t change your rankings one way or another."
The answer is loud and clear. I have not tried testing the index page, so if you did, please let us know your experience (even with that guarantee I am VERY wary of testing the index, since it’s obviously the most important page of the website).
Also, here is a quote from ThreadWatch, quoting Google:
"Website Optimizer is designed to keep your original content visible in the HTML source code of your page at all times. As a result, your original content is visible to crawlers, which means there should be no major impact on search engine ranking."
Apparently GWO and Google Search are integrated, and Google knows when you’re testing and won’t penalize you (an extremely WILD guess). On the other hand, once tests are successful and you implement changes to the original file, don’t be surprised if rankings change, either positively or negatively.
Google Optimization 
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