[alwayshumans]

I think the concept of a persona has morphed and been abused over time.

With my team we use them as a tool to organise a set of assumption's or hypotheses that we want to test. Then through further user research tools we look to validate these assumptions.

On the whole it's not perfect but it works well most of the time.

[Reebz]

This is how I use them too. Personas are the idea or target, you validate the persona against the data collected related to segments/cohorts, etc. Drift of cohorts from personas shows a change in behavior that needs to be understood.