We use persona scales to analyze user goals, behaviors and attributes from user research. The activity goes something like this:
Identify goals, behaviors and attributes we learned about in our contextual inquiries (particularly where there are distinctions between users to whom we spoke).
Place the above on a continuum with either end representing the extremes we learned about (not that exist but that we specifically learned about in our research).
Place each user research participant on each continuum.
Look for patterns where the people we talked to end up being grouped together often. Circle the patterns -- each group in a different color works well.
Each grouping identifies an archetype / persona.
We used three different scales, one for each role. Though roles won't always map to personas, in this case each role had such different goals we decided it was a good starting place that allowed us to simplify the data: