When it comes down to deciding what you should be testing, there are some useful mental models to keep in mind. Before you begin building anything, consider the process hypothesis-validation loop you are going through during your interviewing phase.

The hypothesis-validation loop

During an interview, your goal is to gather information, then you take that back to your team to extract insight, and finally you develop a hypothesis that you should test by more gathering information and so on.

As you begin to develop your prototypes and collect market data, it becomes apparent that the information you gather doesn’t just come from the customers interview. In fact you are combining the interviewies with prototypes, market data, and your own experience to generate valuable insights.

Imagine that when you are out collecting information your view is expanding —or diverging. After you hit a critical mass of information, you narror your view — or converge into an insight. This constant diverge and converge cycle was observed in the design process of eleven leading companies by the Design Council, a United Kingdom charity incorporated by Royal Charter, that arrived at a proccess call the ‘double diamond’.

The ‘double diamond’ design process model

The double diamond was developed after years of search by Britain’s Design Council. It’s divided into four distinct phases, Discover, Define, Develop and Deliver to map the divergent and convergent stages of the design process, showing the different modes of thinking that designers use.