One of the biggest things affecting a school’s exam results is not what happens inside the classrooms: it’s the backgrounds and circumstances of the children the school lets through its gates in the first place. The more children from poorer families a school has, the worse its exam results tend to be.
The graph below shows almost every state secondary school in England . It plots how many of each school’s pupils qualify to receive free school meals against how many of each school’s pupils get at least five A*-C grades at GCSE including English and maths. Roughly speaking, it plots poverty against results .
There’s a pretty good correlation, of -0.57, between how many pupils are on free school meals and how many get five A*-Cs including English and maths. As poverty rises, exam results fall (although this fall levels out after around the point where a fifth of a school’s pupils qualify for free meals).
The grammar schools skew the picture – but only a little. Among comprehensives, the correlation is -0.55 – only slightly lower.
Most grammar schools are clumped up in the top left corner of the graph. They get very good results, which is hardly surprising given their intake. But selecting for ability also tends to select for wealth. The average selective school has just 2.6% of its pupils on free meals, while comprehensives average 16.7%. In fact, there’s not a single grammar school in all the land with even three-quarters as many kids on free school meals as the average comprehensive.
The next graph tells a similar story to the first, but it just covers comps, and it gets rid of a lot of the noise by grouping together schools by how many children on free meals they have (0-0.9%, 1-1.9%, 2-2.9%, 3-3.9% etc.) and shows the average results score for each such group:
But the correlation figures above understate the strength of the relationship. There are wide regional variations in prosperity across England, and of course parents don’t navigate the education system on a national scale: school choice works locally.
So by breaking the figures down into individual local education authorities (LEAs), we can see how strong the relationship is between poverty and results on a scale more relevant to parents’ choices about which neighbourhood to live in and which schools to apply to.
I’ve checked every LEA with 20 or more secondary schools (the smaller they are, the less reliable the correlation stats become ). There are 45 such LEAs, out of a total of 150.
The correlations range from -0.57 (Cornwall) to -0.90 (Leeds) – with an average of -0.76. So if you look into an individual LEA, the local link between poverty and results is usually much stronger than across England as a whole .
(LEAs with selective schools appear to have only slightly stronger poverty-results correlations than all-comprehensive LEAs.)
All this just shows how strong the link between poverty and GCSE results is. The exact nature of the causation is more complex to untangle, but it’s going to involve the fact that struggling to make ends meet makes it harder to devote time and resources to one’s children’s development. It’ll also, conversely, involve the fact that schools with good results become oversubscribed, driving local house prices up so that these schools become fuller and fuller of children with well-to-do parents.
One way to stop the education system from segregating children is to prevent popular, higher-scoring schools from cherry-picking the most promising ones. Banding and lotteries are efforts to achieve this, but I’m not aware of any compelling evidence either way on their effects.
The government’s big plan is the pupil premium, Nick Clegg’s favourite boast but something that appeared in all three main party manifestos in 2010. It’s an interesting way to motivate higher-scoring schools to admit more poorer pupils. Whether it succeeds or fails will depend on whether the extra cash can overcome the fear of being dragged down by the chavs.
 2009/10 data, from the ‘Secondary’ tab of the ‘School spending – all data’ spreadsheet produced by the Department for Education. I’ve had to take 23 schools out of the calculations as there aren’t exam results figures for them.
 Qualifying for free school meals is an imperfect measure of poverty, related as it is to receipt of certain benefits. But it’s a decent indicator. Also, there are many other ways to measure how good a school’s results are than the number of kids getting five A*-Cs including maths and English: you could raise or lower that bar as you liked. This, however, is the data I have.
 Out of curiosity, I also looked at each of the 26 LEAs with under 10 schools in the data set. All have similarly strong negative correlations, for whatever that’s worth – except for the odd (but tiny) outlier of the Isle of Wight, whose five schools form a decent line sloping the other way, for a correlation of +0.51. I don’t know what, if anything beyond random variation, is going on there.
 How can pretty much every LEA have a stronger correlation between poverty and results than the national figure? Simple. This chart shows the schools in Bradford and Northamptonshire:
The red dots are pretty clearly grouped around a line (Northants has a correlation of -0.81), and so are the blue dots (Bradford’s is -0.76). But they’re different lines: Bradford is, on the whole, poorer and has more schools getting lower results, but with increasing poverty making less of a difference among its schools than in Northants.
So putting all the dots together blurs the clarity of the lines a bit: the overall correlation across the two LEAs between poverty and results is -0.73 – still high, but lower then either alone. The same thing happens, on larger scale, when looking at all the schools across England together.