Creating as an issue to document changes...
There's some concern that highest-educational-attainment prediction models seem to under-predict high-attainment at later ages and over-predict medium-attainment:
Insensitivity of some models to predict the higher age groups may be partially down to low numbers of observations in estimate population:
Would suggest having an age-26/27 cutoff, where all leaving (first) education after this are assigned 'High' educational attainment?