Monday, 3 October 2016

Brewdog: Stick to the Beer

I've written about non-normalized choropleths before (e.g. here and here and here) but when one of my favourite breweries makes the mistake I feel compelled to mention it again.

Brewdog are setting up in the USA. This is a good thing because their beer is spectacularly good. I have become an investor in their USA Equity for Punks campaign to support their efforts. But they need a cartographer because their maps are spectacularly bad.  They've been running this map showing how investors are spread across the US.




Clearly they're mapping totals as a choropleth which as most who know me will know gets me really rather upset. I mentioned this to Brewdog but their reply suggest (a) they don't get it and (b) they don't care.


Yes, I get that it's a bit of a fun but that's not actually a good excuse for making a crap map.  I could make some shitty home brew just for fun as well but what's the point of that? I'd rather try and do the job right and make something that tastes good. They've also used a poor blue to red colour scheme but that's a different argument. Anyway, I have offered to help them correct it so just because I can, here's a couple of efforts whipped up in less than an hour.

Here's the (incorrect) totals version as a choropleth in Punk IPA colours:



And here's the same data of the number of investors, normalized by the number of people over 21 (drinking age) in each State to create a 'Punks per Million' map. I guessed on roughly what the data might be from their original map:



Compare thee two maps. You see - because the population of each state differs massively and the size of States differs massively, using totals inevitably skews the map numerically and visually and you get a warped sense of reality. Texas will always come out as a lot. Montana always not. But actually, as a proportion of the population, there are more Punk investors in Montana than Texas. Ohio still gets shown as having the most investors because they have a lot (as totals) and as a proportion of their population and that's where the new brewery is. But California isn't a stand-out because it has roughly the same Punks per million as Oregon and even Wyoming.

Still want to map totals? Well use a proportional symbol map:



There you go - now you can clearly see the huge difference in the pattern of investment between states. And if you want to Punk out the map...well go right ahead:


And yes, I used the same bottletop technique on this quick map as I did on the much larger Breweries of the World map which, if you want a copy, can be downloaded here.


So, Brewdog. I like your beer a lot. You take great care to make it right. I like maps a lot and I take great care to make them right. You stick to brewing and I'll keep drinking your beer. I'll stick to making maps. If you want some help with the maps, just drop me a line.





2 comments:

  1. Question: what is it about the proportional symbol map that makes it OK to apply raw totals to maps, vs. a choropleth? I feel like I have not heard this clearly articulated (which is not to say I am arguing against it; just that I don't really have a good case for it). It seems like your description of "Texas will always come out as a lot. Montana always not" applies to the proportional symbol map just the same.

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  2. Hi Daniel, the symbols in a proportional symbol map are uniform shapes that scale relative to one another so totals work fine. Percentages will also work fine and you,re right that they will account for unequal populations. Because the shapes, sizes and areal extent of the 'data containers' on a choropleth are fundamentally unequal, totals will alwyas be warped further. Normalizing to create a per capita rate....or a ratio, takes account of this. It goes a long way to ameliorating the problem of different population sizes in different sized areas. Of course - a cartogram does an even better job but let's not get into that.

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