For performance information to be of any real value it should be focussed on what the school does for children that attend regularly and whose parents provide an appropriate level of support.
Competitive admissions, which are the inevitable consequence of the 1988 Education Act, ensure that such children are not evenly distributed through the system. It has always been unreasonable for schools to be called to account for poor attendance and then penalised in league tables for results that absent pupils don't achieve.
It is even more outrageous to include hostile, addicted, unhealthy and disinclined pupils in comparative value-added measures because the presence of overt and covert selection concentrates such children in particular schools.
The solution is to confine value added calculations to pupils whose attendance at lessons relevant to results is at least equal to the government expectations and whose parents comply with home-school agreements.
To the charge that heads would screen out the pupils that don't contribute positively to the school's performance should come the retort that selective schools do this before they are admitted in the first place.
1 Rowe Head Court