AB Testing and Search Engine Optimization

  • Updated
  • Optimizely Web Experimentation

Google encourages A/B testing and believes that performing an A/B or multivariate test poses no inherent risk to your website’s search rank. However, you can jeopardize your search rank by abusing an A/B testing tool for purposes such as cloaking. Google has articulated some best practices to prevent this:

  • No cloaking – You should not use an A/B testing platform to change the spirit of the page. If Google determines that the variation of your page is substantially different from the original in scope and content, then they may construe this change as cloaking, and your site may be subject to a penalty. However, according to Google, “Google encourages constructive testing and does not view the ethical use of testing tools such as Optimize to constitute cloaking. Optimizing your web pages benefits site owners as well as users by increasing conversions and by presenting the most desired information more efficiently.”
  • For experiments involving redirects, use the rel=canonical tag – If an A/B test has multiple URLs, place the rel=canonical attribute on all alternate links, pointing to your original page. This helps bots indexing your website to find your original page. Experiments involving redirects should be fine as long as they do not redirect to unexpected or unrelated content. See Google's article on sneaky redirects for more information.

The snippet's load times and effect on SEO

Site speed is one factor that Google evaluates for its search rankings. Since Optimizely Web Experimentation is executed front-end and loads synchronously, it should not have an impact on the SEO rankings of your site. You can also check Optimizely Web Experimentation's best practices on how to implement the snippet to optimize the loading speed of your snippet.

How long to run an experiment

If you are running an experiment for an unnecessarily long time, Google may interpret this as an attempt to deceive search engines and take action accordingly. This is especially true if you serve one content variant to a large percentage of your users. Since Optimizely Web Experimentation uses JavaScript for its redirect, it does not pass any link value to the new page. If you are happy with the way the variation is performing, you should do one of the following:

  • Update the content of the original page with the content from the winning variation. This is the best option as it preserves all link equity. You may still see a loss in ranking if the variation is significantly different from the original or has less content.
  • If changing the original page is too difficult or time-consuming, you should put in a 301 redirect from the original page to the variation of the original. A 301 redirect results in a small loss of link equity (around 10%) but should help preserve rankings versus a JavaScript redirect like Optimizely Web Experimentation which passes no link value.