I agree that Progress 8 can be misleading but it wasn't used in reaching my conclusions. I added the P8 rows for completenessThere are fundamental issues in these assumptions based on your statistics.Impact of Selectivity on Performance: Highly selective schools spend less time addressing foundational academic challenges that non-selective schools often face. Instead, they can focus on challenging their high-achieving students to reach the highest grades, setting uniformly high expectations and achieving consistent top results across the board. In essence, the more selective the school is the more they can "hot house" the kids and the better the results. Note that the high performing non selective schools all have some form of implicit selection - (see notes below)
For the most highly selective schools, the intake cohort is not merely based on average higher prior attainment but rather on the upper spectrum of high attainment. In other words, the high prior attainment cohort for QE or HBS will be further to the right of the distribution of the high attainment compared to DAO or Latymer cohort because of higher selectivity. So the prior condition on the high attainment is not on the same basis in the first place.
In addition, Progress 8 can indeed be misleading, because there is an intrinsic high correlation between higher attainment and higher progress. Students who start with higher attainment tend to show higher progress, not necessarily because the school or the environment is making a significant difference, but because they have a strong starting point. This high correlation between prior attainment and subsequent progress skews the data.
It would be more meaningful to see the less selective school have higher progress 8 score but not vice versa.
In terms of Selectivity on Performance, HBS and QE Boys don't have to deal with a significant FSM/SENS/MUSIC/ECHP cohort admitted under lower academic standards. My view is that this allows them to further "hot house" (less factors which dilute academic focus) the kids to get consistently high results. The alternative view that the better results is just down to the higher cohort intake selectivity (better base line) could also be correct however we don't have the data to untangle these 2 factors.
However, irrespective of the above, the overall conclusion still stands : The more selective the school the better is it in terms of GCSE academic results.
Statistics: Posted by YetAnotherDad — Fri Nov 01, 2024 2:39 pm