How many pupils does Ofsted guide to the ‘wrong’ school?

The problem

I have been thinking about the exemption from routine Ofsted inspections introduced for Outstanding schools in 2014.

Inevitably, some of these schools are no longer Outstanding, but we do not know which ones so some families choose the ‘wrong’ school. How many pupils have been affected?

Before I get into the detail, I want to confess my sympathy for Ofsted as an organisation and their staff. I am not ideological about inspection, and I dislike that Ofsted is often seen as the ‘baddies’. However, I am sceptical that inspections add much value to the school system or are cost-effective. For me, this is empirical, not political.


We can get our bearings by looking at how many pupils go to schools split by their inspection grade and the year the grades were awarded. I have excluded the lowest grades for clarity.

So, a little under 1.3 million pupils attend Outstanding rated schools, which on average were inspected in 2013, but some go back to 2006.

Note that I am using data that I downloaded from Get Information About Schools a couple of months ago. This data also takes a while to filter in from Ofsted, but the most recent inspections are irrelevant given the assumptions I explain later.

Estimating the size of the problem

This will be a rough estimate, so I want to be transparent and show my working. You’re welcome to offer a better estimate by changing some of my assumptions, adding more complexity or correcting mistakes – although I hope I have avoided mistakes!

I’m interested in two related questions:

1. How many pupils have joined schools that were not actually Outstanding?

2. How many pupils have joined schools that were not actually Outstanding but chose those schools because of Ofsted’s guidance?

1. How many pupils have joined schools that were not actually Outstanding?

We need to start by recognising that this is a long-term issue, so we can’t just look at the pupils in school today: we need to estimate the number that has passed through the school. To do this, I will assume that the cohort size in each school has remained constant.

The table below shows the number of pupils by the year their Outstanding grade was awarded. I have estimated the number in each year group as one-sixth of the total. I have then calculated the number of year groups affected.

So far, I don’t think anyone would disagree much with these approximations, although you could give more precise estimates.

Next, I need to make two assumptions concerning:

  1. How long a school remains Outstanding
  2. After this period, the proportion that is no longer Outstanding

I want my estimate to be conservative, so I will say that schools rated Outstanding remain Outstanding for five years. After that, half are no longer actually Outstanding. This second estimate is a bit of a guess, but it mirrors an estimate by Amanda Spielman.

So, if we put these two numbers into our simple model, we get the following table, which estimates that 280,000 pupils have joined schools that were not actually Outstanding.

Even if we make very conservative assumptions, this issue still affects a lot of pupils: it’s the classic multiplying a big number by a small number is still quite a big number situation.

Suppose all schools remain Outstanding for seven years, and after that, just 25% are no longer Outstanding; this still affects 75,000 pupils.

2. How many pupils have joined schools that were not actually Outstanding but chose those schools because of Ofsted’s guidance?

To answer this question, we need to multiply our answer to question 1 by the proportion of pupils who have gone to a different school based on the Outstanding rating. My best estimate of this is 10%, which would mean around 28,000 pupils.

My estimate is based on multiple sources, including comparing differences in the ratio of pupils to capacity between Good and Outstanding schools. This is the estimate that I am least confident about, though. Note that this is an average estimate for the population: individuals will vary a lot based on their values, priorities and their local context – especially their available alternative options.

So what?

First, I’m very open to better estimates of the magnitude of this issue, but I think this issue is an issue. Again, this is empirical, not political.

Second, defenders of the Outstanding exemption policy might reasonably argue that it refocused inspection by allowing more frequent inspections of poorly rated schools. The trouble with this argument is that Ofsted has never generated rigorous evidence that inspections aid school improvement. This would be a fairly simple evaluation if there was the will to do it – you could simply randomly allocate the frequency of inspections – but it is easy to understand why an organisation would be unwilling to take the risk.

Third, this issue is not over. Today, tomorrow, and next year, families will choose schools for their children based on Ofsted results, and some will be mislead. Even with the accelerated timeline for post-pandemic inspections. Not to mention the myriad other challenges to making valid inferences. There is also a risk of the reverse happening: families being sceptical about older Outstanding grades and placing less weight on them in their decision-making.

Fourth, if Ofsted had a theory of change that set out their activities, the outcomes they hope to achieve – and avoid – and the specific mechanisms that might lead to these outcomes, we could have more grown-up conversations about inspection. To judge Ofsted’s impact and implementation, we need to understand their exact intent.

Finally, as part of the promised review of education, we should think hard about these kinds of issues and how to minimise their impact.

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