Does the New Google Analytics Plugin Also Block Google Website Optimizer Tracking?

By Janet Driscoll Miller | Jun 15, 2010
More Articles by Janet


Since the recent announcement of the availability of a plugin to block Google Analytics tracking, I’ve had one thing on my mind: will the plugin also block tracking information from Google Website Optimizer?

As an avid A|B tester and conversion rate optimizer for both organic and paid search, I am an avid user of Google Website Optimizer. It’s a fantastic, free tool that easily allows website owners to learn about which elements, messages and designs convert more visitors.

I’ve been asking Google (through various channels) for weeks now how (if at all) the new Last week at SMX Advanced, I was fortunate enough to be on a panel with Matt Cutts. While Matt didn’t readily have the answer, he made a good point: check the tracking cookie. Since the purpose of the analytics plugin is to block the tracking cookie, why not compare the cookies that are blocked from Google Analytics to those of Google Website Optimizer? If they are the same cookies, then they would be blocked too. But if not, perhaps all would be OK.

After doing my own testing, here’s what I found…The Bad News

I know most of the time people give you the good before the bad, but in this case, I have to share the bad before the good. The bad news is that the Google Analytics cookie-blocking plugin blocks BOTH cookies from Google Analytics AND Google Website Optimizer.

How Can You Tell?

I decided to conduct my own test to see if my information was blocked from Google Website Optimizer. To do so, I set up several “dummy” pages to conduct a standard A|B test in Website Optimizer and added the tracking code to the appropriate pages. Next, I downloaded and installed the cookie-blocking plugin. Then came my first red flag:

Google Analytics Plugin

So what does this mean? If you’re familiar with Google Analytics and Website Optimizer, you’ll know that the code for each program that you include on your web pages uses a javascript named “ga.js”. For example, in Google Analytics, the line appears as:

document.write(unescape("%3Cscript src='" + gaJsHost + "google-analytics.com/ga.js' type='text/javascript'%3E%3C/script%3E"));

And appears similarly in Google Website Optimizer’s tracking portion of code:

if(typeof(_gat)!='object')document.write('<sc'+'ript src="http'+(document.location.protocol=='https:'?'s://ssl':'://www')+'.google-analytics.com/ga.js"></sc'+'ript>')

So essentially, the plugin is blocking the ga.js file from loading. It is the ga.js file, too, that performs all of the tracking and creates the cookies for both Google Analytics and Google Website Optimizer. Therefore, Website Optimizer also will not track conversions or visits if the plugin is installed by the visitor.

I later confirmed, after installing the plugin and visiting/converting on my test pages, that indeed, Google Website Optimizer was NOT tracking my visits or my conversion actions.

However, it’s not all as bad as it might appear…

The Good News

Before you go crazy about this new wrinkle, know that all is not lost on Google Website Optimizer tracking.

First, many in the SEO and web communities have been discussing the issue of how many website visitors will actually be using the cookie-blocking plugin. How will it change our tracking? While it is impossible to know right now how many people will actually use the blocking plugin, it has not been widely publicized, therefore the impact may be minimal.

Second, for Google Website Optimizer, this plugin doesn’t affect the page serving options. In other words, even if a visitor has the plugin installed, the Website Optimizer will still serve the appropriate A|B or multivariate versions as designed. However, visits and conversions from those with the plugin installed will not be tracked.

So what does this mean for testing and tracking? It means that you can still use Google Website Optimizer and have faith in your testing. It simply means you may have to wait longer to amass an adequate sample size to make informed decisions about your web pages.

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