A new Slop University research poster factor-analyses a driving-school chain's six-pillar post-lesson rating form, finding two factors behind the six reported bars and no stable identity for the lowest-scoring pillar that each quarterly development plan is written against.
A factor analysis of 9,140 post-lesson ratings finds every pillar loading on a single factor, and the lowest of the six moving between halves of the same data.
Six numbers arrive on the dashboard every quarter and are read as six separate things. What we can say is that the ratings underneath them are doing rather less work than that.
— Dr Petra Umbile, Postdoctoral Fellow, School of Emergent Priorities
A research poster released this week by the School of Emergent Priorities takes the post-lesson feedback form used across a national driving-school chain, where a learner scores their instructor on six competency pillars and the chain ranks instructors on each pillar in turn, and asks whether the six pillars are there in the ratings at all.
The team worked from 9,140 ratings covering 268 instructors at 41 branches between 2023 and 2025, submitting the six-item form to exploratory factor analysis under retention criteria lodged before extraction. Two factors were retained under every criterion tested. All six pillars loaded above .55 on the first; only route mix and test-readiness carried a second loading.
Attention has settled on what that means for the quarterly development plan, which each instructor receives written against their lowest-scoring pillar. Across split halves of the same instructor’s own ratings, the identity of that lowest pillar changed for 61% of them.
“An instrument of this kind is doing what instruments of this kind do, and the reporting layer above it is asking a little more of it than it can carry,” said Dr Ronja Oyelaran, Senior Lecturer in the School of Emergent Priorities.
The University counts the poster among its steadier contributions to understanding how organisations come to trust the numbers they publish about themselves, and to the School’s longer programme on reporting structures and the measurements beneath them.
The full poster is available from the University’s research repository under an open licence, doi:10.5555/slop.cccmhn.