There are good reasons why a lot of testing fails to make an impact or shift business metrics, particularly where a site has a mixture of tablet, mobile, desktop and laptop visitors. Testing across multiple device experiences requires deep customer knowledge, careful analysis and superb device QA testing. There are also useful tools and insight methods that are vital to improve the quality of ideas that go into your tests. Responsive or multi-site device experiences give us specific challenges when it comes to split testing. Getting a test to actually work across all customer browsers and devices is really hard and there are some simple mistakes you should avoid, if you don't want to waste your valuable testing resource. Get some useful pointers about where things go wrong and simple rules your team can follow for running tests and analysing the results. Craig shares the mistakes he's made in 10 years of testing, so you can trade wasted time for greater insights, better results and a happier team.