Map #81: March 12, 2018

Difficulty Level: 9

Click here for a full-size version of this week’s map.

This map is a choropleth of the postcode areas of England and Wales. (Do you need a refresher on what a choropleth is? Visit our “Basics” page for a quick primer.) This is a fairly tricky map with a lot going on. It will be difficult at first to discern any coherent pattern, but there are some interesting trends that we’ll talk about in the hints. As always, your job is to figure out what statistic is represented on this choropleth.

Ready to submit your solution to this map? Click here to be taken to the submission page.

Stumped? Check back Tuesday, Wednesday, Thursday, and Friday for hints about where to focus your investigation. The answer will be posted on Monday, March 19, 2018. Good luck!

Monday’s word of caution: England and Wales share a census, but Scotland has its own. We used data from the England and Wales census. This source complicates things for the TD postcode area, which includes areas of both England and Scotland. Our map shows the entire area, but the shading reflects only the portions of that postcode area that are in England, since only the English residents responded to the census of England and Wales. The TD postcode area ended up as the darkest area on our entire map, so your eye will probably be drawn to it right away. Be very wary of drawing too many conclusions from incomplete data. In fact, you would probably be better served ignoring this area entirely.

Tuesday’s hint: Let’s start by looking at the southern half of this map because that part is much, much easier to make sense of. You have probably already noticed that the lightest areas are toward the center of the city of London. The map tends to get darker and darker as you move farther away from London. To some extent, a similar trend is visible in Wales. There, the area around Cardiff is lightest, and it gets darker as you move away from the center of the city. What might explain this trend?

Wednesday’s hint: Here’s a hypothetical situation to ponder. Let’s say you just got a job right in the heart of London. You may not be able to afford to live right in the center of the city, but that’s okay because London has one of the best subway systems in the world and the United Kingdom as a whole has a reasonably efficient network of railroads. Where might you choose live?

Thursday’s hint: This map, as you might already have guessed, has to do with transportation—though not with any particular mode of transportation.