A/B Split testing, or multivariate testing, is arguably the most powerful tool in an online marketers bag of, er, tools. It is essentially putting one pitch up against another and seeing which one does the best. By doing lots of A/B Split tests over time and always keeping the better performer, you can evolve a pitch that is tailored to your market and likely better than a pitch created based on a hunch or intuition. (Careful here; hunches and intuition are not to be discounted. You must start from somewhere, you can’t split test a blank Adwords ad or a from with no fields. And it’s obviously better to start from a good place than not, which is something only a good copy writer can do.)
One of the easiest places to do this is with Google Adwords. They make it very easy to run one ad against another. You can see in the example above, ads for the keyword “right-side back pains”. You would run two different ads (ad A & B, natch) to appear when users searched for that keyword, and see which ad performed better. Then you would eliminate the poorer performer of the two and start testing again. All A/B split testing is some variation of this process.
A/B split testing is also applied to whole web pages or individual elements on a web page like a headline or form. You can see a good example of on-page element split testing here: Writing Decisions: Headline tests on the Highrise sign-up page. They did a multivariate test with lots (more than two) of variables. This is a more advanced form of split testing. (It is much easier to keep track of variables and to vet your data with an A/B split test, which is why it is so much more common.)
Split or multivariate testing is comparing things against one another to determine a superior so that the inferior may be disregarded. By running concurrent split tests of marketing pitch’s, ads or design we can allow our market to determine a pitch that is targeted and effective. (It should also be noted that split testing is a whole discipline, in and of itself, and this is bascially a light primer or vocabulary lesson.)