Nelio A/B Testing adds a tracking script at the very beginning of your website’s HTML structure. We do this so that it (hopefully) runs before any other scripts, including Google Analytics.
When our tracking script runs, the first thing it does is check if the current page is under test. If it is, it performs a JavaScript redirection to a different URL that will include some testing parameters in your URLs.
These parameters tell Nelio A/B Testing which variant has to be loaded for each visitor. For instance, if you created a headline test for your Foo post and added two alternative headlines, you’ll end up having the following URLs:
https://example.com/blog/foo/?nab=0is variant A (i.e. the control version)https://example.com/blog/foo/?nab=1is variant Bhttps://example.com/blog/foo/?nab=2is variant C
Thus, if a user accesses http://example.com/blog/foo/?nab=1, she’ll see the alternative headline B:
Which pages contain the nab parameter?
When creating a new test, you can define its scope. The scope of a test defines the pages in which alternative content from that test can be loaded. For example, if you create a Menu test, by default all pages of your website will be included in its scope, because there’s a chance that all your pages include the tested menu.
The nab parameter will appear on any page that is part of the scope of your running tests. Thus, for example, when running a Menu test, all your pages will include the nab parameter by default.