I’m a big proponent of using both qualitative and quantitative data, but I have to admit that qualitative feedback can be a challenge. Unlike a product funnel or a revenue graph, qualitative data can be messy and open ended, which makes it particularly tough to interpret.
For the purposes of this post, qualitative information is generated by the following types of activities:
- Usability tests
- Contextual Inquiries
- Customer interviews
- Open ended survey questions (ie. What do you like most/least about the product?)
Insisting on Too Large a Sample
With almost every new client, somebody questions how many people we need for a usability test “to get significant results.” Now, if you read my last post, you may be surprised to hear me say that you shouldn’t be going for statistical significance here. I prefer to run usability tests and contextual inquiries with around five participants. Of course, I prefer running tests iteratively, but that’s another blog post.Analyzing the data from a qualitative test or even just reading through essay-type answers in surveys takes a lot longer per customer than running experiments in a funnel or looking at analytics and revenue graphs. You get severely diminishing returns from each extra hour you spend asking people the same questions and listening to their answers.
Here’s an example from a test I ran. The customer wanted to know all the different pain points in their product so that they could make one big sweep toward the end of the development cycle to fix all the problems. Against my better judgment, we spent a full two weeks running sessions, complete with a moderator, observers, a lab, and all the other attendant costs of running a big test. The problem was that we found a major problem in the first session that prevented the vast majority of participants from ever finding an entire section of the interface. Since this problem couldn’t be fixed before moving on to the rest of the sessions, we couldn’t actually test a huge portion of the product and had to come back to it later, anyway.
The Fix: Run small, iterative tests to generate a manageable amount of data. If you’re working on improving a particular part of your product or considering adding a new feature, do a quick batch of interviews with four or five people. Then, immediately address the biggest problems that you find. Once you’re done, run another test to find the problems that were being masked by the larger problems. Keep doing this until your product is perfect (ie. forever). It’s faster, cheaper, and more immediately actionable than giant, statistically significant qualitative tests, and you will eventually find more issues with the same amount of testing time.
It’s also MUCH easier to pick out a few major problems from five hours of testing than it is to find dozens of different problems from dozens of hours of testing. In the end though, you’ll find more problems with the iterative approach.