Monday, 1 August 2011

The law of diminishing returns



Once you've optimised a page using either multi variant testing (MVT) and/or split testing (A/B Testing) and managed to achieve a respectable uplift in sales conversion, when it comes to revisiting that page with further testing, likely as not you're entering the realm of Diminishing Returns.

This is historically an economics term but it also applies to web optimisation testing. This is where subsequent testing or optimisation activities prove to be less rewarding in terms of finding web content that works than the original or earlier rounds of testing.

This has been recently illustrated last week when a colleague produced a new version of an optimised landing page. He wisely wanted to test that it could perform as well as the existing page or even better. The original page was the result of several rounds of previous optimisation testing and was already proving to be very good at converting visitors to submit an on-line application. The image below sees the ongoing split test as conducted in Google Website Optimizer . The original or default page is proving hard to beat, the new page (variant 1) is bettering the original but it's not pulling away in a massive uplift as you might see in the first or second rounds of testing.


It's important to realise that while you should always look to be frequently testing your pages, previously tested or otherwise, as part of a continued programme of testing, we should realise that the big headline results of earlier testing should start to decline test on test . This is a sign of successful testing, indicative that you're starting to get things right from the visitor conversion perspective.

As a very rough guide I would say the following is true for a successful roadmap of testing; Let's call it the ARSSS  approach (sorry I'm such a child!):
  1. Analyse your site metrics, establish user journeys, understand what's going on.
  2. Rationalise your site. Remove unnecessary  pages and clicks. Remove obvious leakage points in your sales funnel.
  3. Start MVT testing. Use this to get under the skin of the user experience. Do as many rounds of testing as it takes to answer your questions and hopefully start to improve your conversion. In essense you're starting to narrow and hone your sales funnel.
  4. Start split testing. Once you know what works on a page element by element basis through MVT you can start to use A/B testing to start look & feel testing entire pages.
  5. Segment Users. Once you've done all of the above start to get into User Segmentation, ie. start to group your customers into segments based on behaviour (I'll be writing a more in-depth post on this in the future).
Happy testing!