Progress 8 is an improvement. The proportion of 16-year-olds gaining five A*-C grades at GCSE, including English and maths, was always a bad performance measure.
Like all threshold measures, it created the perverse incentive to concentrate on students just below the threshold: the grade C borderline.
While there was benefit to the school in raising a grade D to a C, there was no recognition for B-grade students raised to A, or E grades raised to D.
Like the unfair distribution of funding between local areas, it was a lazy policy based on historical factors, in this case five GCE O-levels, the threshold to obtain entry to many jobs or school sixth forms up to the 1980s. It is 27 years since O levels were abolished, but the five A*-C threshold has remained in place.
The reputation of a school – and the job of the headteacher – has for far too long depended on a bad performance measure. Given the high stakes nature of the accountability system, resources were, understandably, focused on some students more than others, who may well have been more deserving.
As a headteacher in the 1980s and 1990s, I would always focus my September analysis of the GCSE results less on the five A*-C measure and more on the average points score of students’ best eight GCSEs. I wanted to stress to staff that every child mattered.
But that was in a school where the results were never likely to dip below any government floor target, and I understand the pressures on heads to focus so much effort on the C/D borderline.
In my role as the Association of School and College Leaders' general secretary, I had to support too many heads whose jobs were endangered by a bad accountability measure.
ASCL campaigned for many years for it to change to an average points score of students’ best eight GCSEs (including English and maths), an output performance measure with virtually no perverse incentives that gives equal credit to improving students’ grades at all levels.
Attainment 8 is not far removed from this and Progress 8 rightly introduces a starting point into the calculation of the progress of each student.
All performance measures are adversely affected by absent students or those who do very badly, and this is particularly the case with Progress 8, under which a nil return from a single student cancels out the improvement of a grade by at least a dozen students.
According to Dr Rebecca Allen, this factor alone has pushed around 50 schools below the government’s floor standard of -0.5. Most of these schools have highly disadvantaged intakes, where the lives of vulnerable children are more likely to cause them to miss all their GCSE examinations.
It always takes people not working in schools a long time to grasp changes in education policy.
In 1988, I found many local employers who did not understand the GCSE for several years after it was introduced and, a few years later, university admission tutors who did not know that AS was the first half of an A level for a couple of years after applicants had started to put them on their Ucas forms.
With the volume of change in education, one should have some sympathy for those not working in schools if they cannot keep pace. Progress 8 is a complex measure, with decimals and small negative numbers complicating the picture for members of the general public, so it will take time for many people to understand this measure fully.
The way the media treated the Progress 8 was perhaps unsurprising. Most made some attempt to explain to their readers the nature of the new measure, but the focus varied according to the media source's political lines.
Some organisations highlighted the fact that grammar schools were no longer at the top of the Progress 8 performance tables, listing the top performers on the progress measure and highlighting the Tauheedul schools in Blackburn and others with a score of greater than +1, where student attainment had been raised by more than one grade per subject.
By contrast, others highlighted the 282 secondary schools below the government’s new floor standard. Some commented at length on poor performance in the North and used Attainment 8 to show a table with 10 of the most highly selective schools at the top, several of which were pictured. A table of the 10 "worst performing" schools at GCSE comprised mostly special schools.
As Duncan Baldwin, of the ASCL, commented: "Progress 8 resonates with the moral purpose of school leaders – getting the best attainment for every pupil in every subject."
Michael Gove may have expunged the New Labour slogan "Every Child Matters" from the education policy lexicon, but under Progress 8 every child matters more than ever in their attainment. And that can only be a good thing.
John Dunford is chair of Whole Education, a former secondary head, general secretary of the Association of School and College Leaders and national pupil premium champion. His book, The School Leadership Journey, was published in November 2016. He tweets as @johndunford
For more columns by John, visit his back-catalogue