I hate to be the devil's advocate but ...

If we asked a client to rate themselves isn't this going
against the idea of not using statistics as we all know it depends
on the biases and techniques of those who create the research project?
Creating statistics is against the idea of 'the whole person' or
the main Adlerian theory of wholistic "Individual Psychology"?
Case history of one client is the only research I believe is valid for
Adler.

I also believe that Adler showed that having verticle relationships
harms the idea of "social interest" and creates competition.
Verticle relationship meant you put yourself on a scale to judge
against others so you were above or below. A horizontal
relationship meant you stood equal in value.

Only horizontal relationships can create true "social interest"
which is a main measure of mental health.