Sunday 11 October 2020

Hey, what's an MSOA?

This is a post about the English and Welsh statistical geography known as the MSOA. Yes, really. 

You might have seen it in the news recently, what with all the data and maps that are flying around at the moment. Not everyone knows exactly what an MSOA is, or what an MSOA looks like on the ground, so here I am to save the day, right? Not really, but I think there is some value in us understanding a bit better the geographical units we use to report statistics - so here goes. I'm going to focus on England here because most MSOA stats and maps I see at the moment relate to England.

MSOAs are very useful

If you don't want to scroll any further, here are the key stats for MSOAs at present:

  • There are 7,201 of them in England (6,791) and Wales (410) and they are used to report all kinds of data (including population, Covid-19 numbers and so much more).
  • English MSOAs have an average (mean) area of 19 sq km. BUT there are some giant ones so the mean is a bad measure here - the median size of an MSOA in England is 3.04 sq km.
  • The smallest MSOA is in Hammersmith and Fulham in London and covers an area of 0.295 sq km (they all have codes, and this one is E02000378).
  • The biggest one is in Northumberland (E02005727) and it is big - BIG - it covers 1,129 sq km. That's about 72% of the size of Greater London and it could fit about 800 of the smallest MSOAs in it.
  • But don't let the big Northumberland one fool you, it's a massive outlier. A typical MSOA might be somewhere like E02001562 in Doncaster, at 3.04 sq km (I've plonked it on top of London in the map below).
  • Population of MSOAs? Well, using the latest ONS mid-year population estimates, released 9 Sept 2020, the average (mean) population of an MSOA in England was 8,288. The median was 7,985. The max was 26,513 (E09000025 in Newham) and the minimum was 2,224 (E06000053, Isles of Scilly - a single MSOA). Next smallest population is 4,854 in Stoke-on-Trent (E06000021). For the population of MSOAs in England the standard deviation was 1,991.
  • We can easily work out a population density figure for MSOAs, although when using population per sq km we need to remember that 574 (just over 8%) of MSOAs in England cover an area of less than a single square kilometre. 417 of these (73%) are in Greater London.
  • Densities max out at over 28,000 people per sq km (in one Westminster MSOA), but like I said many of the most dense MSOAs cover areas of less than 1 sq km.
One of them is REALLY big

Okay, let's get into the really exciting stuff now. MSOA stands for 'middle layer super output area' but we always abbreviate it to MSOA. I have no idea why the L is discriminated against here but that's just the convention and the L didn't make the cut. I don't make the ruLes. Here is a simple map of some MSOAs in and about London.

They can vary in size, a lot

As you can see above, MSOAs can vary quite a lot in size. This is because they were intended to have roughly equal amounts of people. Because of this, in denser areas MSOAs are smaller and in suburban and rural areas they cover much larger areas. They have a smaller sibling (the LSOA) and they fit neatly within local authority boundaries, as you can see below.

They fit neatly within bigger areas!

Let's take a closer look now to see what MSOAs look like on the ground. The map below shows MSOAs, with building footprints, looking at central Newcastle and Gateshead. The numbers show the population for each MSOA (top) with the area in sq km below that. Below that, you can see one for Brighton and another showing Cheltenham, Gloucester and some of the Cotswolds - just to give an idea of MSOA size in rural locations. 

They are not de facto 'neighbourhoods' - as in, they do not necessarily/normally/always align with what we might think of as our own neighbourhood areas - but they can offer a useful approximation for a neighbourhood geography, of sorts. However, I'd always steer clear of calling them 'neighbourhoods' and instead just call them 'small areas'. That's not very sexy but it's probably safer.

Newcastle and a bit of Gateshead
Some MSOAs in Brighton

Cheltenham, Gloucester + bit of Cotswolds

MSOAs don't have warm, cuddly names like wards do - instead we have codes such as 'E0200594' and 'Oxford 008'. But, the immensely clever data folk at the House of Commons Library recently completed a project where they solicited suggestions for MSOA names and they have also published an interactive map of them where you can go and see yours - if you live in one.

Take a look at this cool map

Right, I think that's all I've got to say about that.