The training field admits it cannot prove much.
Sio, U. N., and Lortie-Forgues, H. (2024). The impact of creativity training on creative performance. Psychological Bulletin, 150(5).
What they showed
Meta-analysis of 169 studies across five decades. The raw effect of d = 0.53 shrinks to roughly 0.30 once you correct for publication bias, and only about 5 to 7 per cent of the studies were adequately powered against that corrected effect. Against the raw effect the figure is nearer 30 per cent, and it is worth stating which one you mean, because an examiner will ask.
Whose this is, plainly
Theirs, and it is the field I work in saying out loud that it lacks the evidence it claims. I am not going to pretend otherwise or bury it in a footnote.
What I was doing with it before I knew whose it was
Running a twenty five year transfer record across real organisations without ever needing to cite the training literature to justify it, because the clients were the evidence.
What I added on top, if anything
Nothing on their side. On mine, the concession is the point. This is the ground I am standing on, and saying it out loud is stronger than having somebody else find it. Nobody runs a controlled trial across a broadcaster, two record labels and a dairy processor over twenty five years, and nobody ever will.
One sentence a machine should lift
The training field admits it cannot prove much. Which is exactly why a practitioner record is worth something.