Evidence use

How comparable are Ofsted grades?

What should Ofsted do, and how should they do it?

It’s a perennial question in education. An answer that will often come up in these conversations is that Ofsted gives vital information to parents about the quality of schools.

I am sceptical that Ofsted currently does this very well for two reasons:

  1. It’s tricky comparing grades between years – particularly as the nature of inspections shifts even within a year
  2. It’s not possible to compare inspections between different frameworks

How big is the issue?

Armed with my scepticism, I explored these issues by comparing secondary schools within every parliamentary constituency. I chose constituencies as the unit of analysis since it is a reasonable approximation of the schools a family chooses between. Constituencies have a median of 6 secondary schools (interquartile range: 5-7; range: 2-15).

I turned my two concerns into three binary questions that could be answered for each constituency:

  1. Are there the same grades but from different years?
  2. Are there the same grades but using different frameworks?
  3. Is there an Outstanding on the old framework and a good on the new framework?

I found that the first barrier affects nine out of 10 constituencies. Two-thirds of constituencies are affected by the second barrier; one-third are affected by the final barrier.

Some examples

Let’s look at some examples. Bermondsey and Old Southwark has nine secondary schools – which one is the best? One of the four Outstanding schools, right? Except only half of the previously exempt Outstanding schools have retained their grades so far.

The only inference I would feel confident with is that it looks like any of the choices will be quite a good one – which is fortunate – but it’s hard to argue that Ofsted is doing an excellent job for the families of Bermondsey and Old Southwark.

SchoolYear of inspectionFrameworkGrade
Bermondsey and Southwark secondary schools

Let’s look at Beverley and Holderness. It’s quite the contrast: the schools have been inspected using the same framework and within a year of each other, except for School F, which has no grade. This looks like good work by Ofsted: clear, actionable information.

SchoolYear of inspectionFrameworkGrade
Beverley and Holderness secondary schools

So what?

Ofsted’s role looks like it might be reformed in the next few years, as signalled in the recent White Paper’s promised review of regulations and the new HMCI arriving next year will have their own views. Geoff Barton has pre-empted this debate with some interesting thoughts on removing grades.

I’ve previously criticised Ofsted for not having a published theory of change articulating how their work achieves their desired goals while mitigating the apparent risks. Ofsted do acknowledge their responsibility to mitigate these risks in their recently published strategy.

If Ofsted had a clear theory of change, then informing the parental choice of schools would very likely be part of it. The information presented here suggests that Ofsted are not currently doing a great job of this. In some ways, these issues are inevitable given that around 800 secondaries have an inspection on the new framework, 1,800 have one on the old framework, and 600 do not have a published grade.

If Ofsted had a clear theory of change, then informing the parental choice of schools would very likely be part of it.

However, if Ofsted conducted focused, area-based inspections, they would effectively mitigate the issues of different years and different frameworks for more families. These inspections would involve inspecting all the schools within an area within a similar timeframe. This would enable more like-with-like comparisons, as is currently the case in Beverley and Holderness. There would always be some boundary cases, but it would make it more explicit for families that they are not comparing like-with-like.

It is still possible to combine this approach with targeted individual inspections of schools based on perceived risks. No doubt this approach would come with some downsides. But if we are serious about giving parents meaningful information to compare schools, why do we inspect schools the way that we do?

A bonus of this approach is that you could evaluate the impact of inspections using a stepped-wedge design – a fancy RCT – where the order that areas are inspected in is randomised.


Do Ofsted grades actually influence choices? Yes. Ofsted themselves are always keen to highlight this. There is also a clear association between grades and school popularity, which we can approximate by calculating the ratio of the number on roll to school capacity. A higher ratio means that the school is more popular. The trend is clear across primary and secondary.

Ofsted gradePrimarySecondary
Requires improvement0.850.81
Serious weaknesses0.790.86
Special measures0.790.74

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