Mental models describe behavior that is independent of tools (similarly to Jobs To Be Done). Because it is tool-independent, it remains valid for a long period of time. You should redo the research from time to time though.
It was developed by Indi Young at Adaptive Path.
The Basics
The steps:
- Select the target group
- Monitor user behavior and ask open-ended questions about what the person is trying to achieve
- Write a list of tasks that came out from interviewing and monitoring
- Group tasks according to their affinity to each other
- Give groups a name
- Create a mental model diagram that maps tasks (the problem space) to existing or planned features (the solution space)
How To Measure It
Additionally, you could assign metrics on the appropriate level either to tasks, towers (groups of tasks), or even bigger spaces.