Introduced by the DfE for schools in England in 2016, Progress 8 measures a student's progress between Key Stage 2 and Key Stage 4 across eight key subjects.
It shows whether students have performed to expectation, based on a value-added measure using Key Stage 2 English and Maths as a baseline. It's checked by getting a sample of Year 11 students to sit English and Maths reference tests in March before their June GCSEs.
Attainment 8 measures the achievement of a pupil across 8 qualifications including mathematics (double weighted) and English (double weighted), 3 further qualifications that count in the English Baccalaureate (EBacc) measure and 3 further qualifications that can be GCSE qualifications (including EBacc subjects) or any other non-GCSE qualifications on the DfE approved list. Each individual grade a pupil achieves is assigned a point score, which is then used to calculate a pupil’s Attainment 8 score.
Some argue that Progress 8 is statistically flawed as some external values can be added to skew the apparent school progress and make it look better than it is. However, progress 8 is a way to encourage secondary schools to get students improving.