I read once about a man who tripled his conversion rate by changing a single letter in his headline. While that kind of improvement is not common (not by a long stretch), you can quite probably double your conversion rate after testing 10 or 20 items on your page. With that said, there are many things to consider when getting started with split testing.

I read once about a man who tripled his conversion rate by changing a single letter in his headline. While that kind of improvement is not common (not by a long stretch), you can quite probably double your conversion rate after testing 10 or 20 items on your page. With that said, there are many things to consider when getting started with split testing.

Let me give you an overview, so you can understand the choices you have before you. I'll walk you through the main distinctions that rule the field.

One big distinction is between single variable and multiple variable (multivariate) testing.

With single variable testing you just pick one element on your page to test. Take your headline, for example. If your current headline says "Are you having trouble with tooth decay?", you might want to see how "Do your kids have tooth decay?" works. In a single variable test, you just find a way to rotate each of those headlines on your page, and keep track of how many sales each generates.

Paul Hancox has a simple split testing tool. And Google has one that's free, though it takes a bit to set up all your accounts to use Google's tool. And the reporting is not real-time.

With multivariate testing, you can test many factors at the same time on your page. So, instead of just testing your headline, you can test your headline, your offer, the P.S. statement, and your lead image all at the same time. And with multivariate testing, if it's set up right, you can use the same amount of traffic testing many variables that you would use to test a single variable.

Among multiple variable software solutions, there are hosted plans and self-install plans. If you want to install software on your server (which can be faster and cheaper) you will have more control over your data. And you can usually find someone to install it for you (often the vendor provides this service for a nominal fee). If you want to go with a hosted plan expect to pay more.

Hosted solutions include Google's Website Optimizer, and Vertster. Installed solutions include the Split Test Accelerator and Kaizen Track.

The next distinction probably causes the most confusion among people looking into split testing for the first time. It's also more important than the last distinction, becuase it determines how fast and accurate your tests can be. The three kinds of testers are 1) random independent rotators, 2) Taguchi testers, and 3) full-factorial testers. Taguchi ranks first for speed and second for accuracy. Basically Taguchi testing involves using a marvel of mathematics known as "orthogonal arrays". These have special properties that allow you to test every combination in a space while running only a small fraction of the actual combinations. You have to be a little bit careful about interaction effects with Taguchi testing. The Split Test Accelerator and Kaizentrack are Taguchi testing tools.

If you want to get around interaction effects you can with a full factorial tool. It will take more traffic to avoid the interactions -- a lot more -- but with a FFT, like Google's Website Optimizer, you can just see how every combination plays out, and live with the interactions.

The Taguchi and full factorial tools both use arrays to maintain a relationship between the options being served for one factor, and the options being served for another. Some split testers don't do this, though. They simply treat each factor as independent from the other factors. This leads to more flexible test designs, but also to longer and less accurate tests.

There are other distinctions and features worth noting. And each solution has a different mix of pros and cons. But this should get your oriented a bit before you make your decision.