Split A/B Testing.. Right for you?

During any website usability study a number of usability problems are often found. Any organization can go round and round trying to determine the best way to fix issues, with no one really knowing the optimal solution. Rather than letting the person that shouts the loudest get his or her own way, a better solution can be to test multiple solutions in a live environment. Whichever performs the best is clearly the superior solution. Welcome to split A/B testing!

If you’re managing a website you might face similar situations when you need to decide which of 2 different designs to opt for. Nowadays, you need to continuously improve and evolve your site by making small iterative adjustments. But how do you know which change will have the highest impact on the customer experience?

Split A/B testing is a fantastic way of determining what changes will better impact your users’ performance. It provides a controlled method of measuring the effectiveness (or ineffectiveness) of different aspects of your site. It’s often used for small tweaks (e.g. ‘Is this style heading clearer than the original?’) but can also be used to test bigger wholesale changes (e.g. ‘Is this new 1-click checkout process better?’). In essence, it involves running 2 different versions side by side to see which is more effective.

Typical A/B scenarios

You feel your users might not be finding the ‘Add to Cart’ button below the fold of your page and think it may be causing people to leave your site before completing a purchase. You’ve created a new design which you think could be more effective but you’d like to know for sure.

To A/B test your new layout, you serve the regular page to say 90% of your visitors as usual, but a randomly selected 10% would be shown your new design. Then you sit back, pour yourself an ice cold drink, wait and watch your web stats.

If your new layout has a positive effect as you suspect, then you should see an improvement in the 10% group, as measured by conversion rates. Quantifiable proof that you should publish the more successful page to all visitors.

Advantages of split A/B testing

  • Low risk approach
  • Cheaper than other methods such as focus groups
  • Provides proof
  • Invisible to most of your users
  • Great way to do ‘test run’ new designs before full roll-out (to avoid negative surprises on the launch day)
  • Can solve internal disputes

Disadvantages of split A/B testing

  • New designs might have to ‘wear in’ before you can measure their real performance (visitors’ initial response might be negative because they’re used to the old solution)
  • You can only compare 2 versions with a single factor that differentiates both designs (for more factors / variations you need to deploy multivariate testing which is more difficult to analyse)
  • It takes technical know-how to set up and analyse the results
  • You’re testing in a live environment so external factors might have an impact on the outcome
  • If your site is really in bad shape, you’ll still need to do a proper overhaul

In a nutshell

A/B testing is powerful stuff and a useful method for a quick comparison for 2 different designs. However, bear in mind that it’s no substitute for getting proper feedback from your users.