DESIGN CHECK (test, delete). A worked example of the article shape: a standfirst, an evidence rating, two subheadings, one picture and the field it belongs to.
A formulation is a shared account of why a person is struggling now. It draws together what has happened to them, what they make of it, and what keeps the difficulty going, in language the person recognises as their own.
What goes into it
Most approaches ask a few common questions: what the difficulty is, what set it off, what keeps it going, and what in the person's life and history makes it understandable. Different schools fill those questions in differently, but the questions themselves are widely shared.
It is written with the person, not about them. A formulation the person does not recognise is not a finished formulation.
What it is for
A formulation guides what happens next. It says which of several possible approaches fits this person, and it gives everyone involved a way to notice when the account no longer holds and needs to change.
It is revised as understanding grows. That is a strength of the method, not a weakness: a formulation is a working hypothesis, held lightly, and tested against how things go.