Education Datalab and the Association of School and College Leaders (ASCL) have looked at how Ofsted ratings relate to Progress 8 scores - the government’s new accountability measure - ahead of the secondary school league tables being released tomorrow. Here are some key findings:

1. Schools rated ‘outstanding’ by Ofsted had an average score of 0.47

A total of 735 secondary schools that received Ofsted inspections between September last year (when schools first saw their provisional Progress 8 scores) and June - were looked at for the analysis.

From this data, schools rated as outstanding had an average Progress 8 score of 0.47 - which is above average in the league tables. And schools rated as good had an average score of 0.07.

Schools judged as requiring improvement had an average score of -0.27 and those rated as inadequate had an average score of -0.45. Both scores are below average in the league tables.

The researchers conclude that inspection outcomes were closely related to Progress 8 scores - but that a certain score “does not necessarily determine a certain inspection judgement”.

2. Schools with well above average Progress 8 scores received a mix of Ofsted ratings

Half of the schools with well above average Progress 8 scores (+0.5 or higher) - achieved an “outstanding” rating from Ofsted, meanwhile approximately two-fifths achieved a “good” rating.

But 5 per cent of schools with “well above average” Progress 8 scores were still judged as “requiring improvement” and another 5 per cent received an “inadequate” rating. However, the analysis says that only one school received each of these ratings in the group of 22.

3. No schools with average Progress 8 scores were rated as ‘outstanding’ by Ofsted

None of the schools with Progress 8 scores that were either average (0), below average (-0.5 to 0) or well below average (lower than -0.5) were rated as outstanding by the schools watchdog.

Schools with average scores were most likely to receive a “good” judgement (74 per cent), while schools with below average scores were most likely to receive a “requires improvement” judgement (47 per cent).

4. Concerns about the ‘arbitrariness of the inspection process’ might be allayed

The study concludes that schools might be “encouraged” as the findings suggest that inspections are producing judgements broadly in line with historic assessment data.

“This might allay some concerns about the arbitrariness of the inspection process,” it says.

However, for schools on a rapid improvement journey, strengths in current performance may not yet be reflected in historic results, the study adds.  

The researchers, Steve Rollett from ASCL and Philip Nye from Education Datalab, add: “Some might have concerns that inspection outcomes are coming out too much in line with past performance - and might actually have hoped for a less strong link.”

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