Multivariate testing and SEO

At first sight, multivariate testing appears to contravene Google’s webmaster guidelines. Check our search engine optimization tips first before running multivariate tests.

What Googlebot sees

Google’s webmaster guidelines advise against cloaking. Cloaking is the practice of presenting a version of a Web page to search engines that is different from that presented to all other users. Serving different content depending on the user agent may cause your site to be perceived as deceptive and removed from the Google index.

However, multivariate testing in Website Optimizer does just that. Website Optimizer replaces your Web page’s original content with variations to users who have JavaScript enabled in their browser. Googlebot can only execute a limited number of JavaScript calls and is not at present able to handle multivariate tests. Unethical webmasters could be tempted to stuff their original content with keywords and spammy links for Googlebot, and show only clean content variations to ordinary visitors to their Web site. Click the screenshots to see this in action:

What Googlebot sees:	What your users see:

Google guidelines for multivariate testing

Google has confirmed that it doesn’t view the ethical use of multivariate testing tools such as Website Optimizer as cloaking. However, it suggests you implement the following guidelines to be sure that your experiments don't come across as cloaking:

1. Keep your variations true to the ‘spirit’ of your original page.
2. Continue showing your original page to a non-trivial percentage of users, when running an experiment.
3. End your experiment when sufficient data has been collected, and update your original page soon afterwards to reflect your winning combination.