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.