As a trainee, I'm still trying to get my ahead around these indicators. As I understand it: Attainment 8 is an average of the grades achieved by students in various groups, years, etc. A comparison of Attainment 8 between two years, would show how the groups of pupils in a school are progressing. Progress 8 is not a measure of the progress that a school is making, but a comparison of how a school is progressing against other schools. It is impossible to infer how well the pupils in a school are achieving from the Progress 8 measure. It is impossible to infer how well a school is doing between years, from the Progress 8 measure. A school could have a negative Progress 8 measure, but could still be outstanding and improving. A couple of poor performing students, for whatever reason, could have a significant impact on Attainment 8 and Progress 8, and skew the results significantly.