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A pet peeve about map interfaces


As you may know, May 6 is election day in the UK. As I grew up there I have been taking an informed foreigner’s interest in it, mostly through my favorite online newspaper The Guardian. Browsing around the election coverage I came across a page that reminded me why I hate all the map-based interface demos I see. The page in question is Election map and swingometer allows you to see the impact of various voting patterns on the constituencies.

Now take a look at the map on the left. Looks like the UK and is the kind of map BI and analytics companies would use to show how wonderful their map interface is. If you looked at this map of the previous election your gut reaction would be that the blue party (Conservatives) was the government and that the yellow party (Liberal Democrat) probably beat out the red party (Labour) for second. You would of course be wrong and a glance at the second map (or cartogram) on the right shows you why. THIS map makes each constituency the same size and tries to lay them out to more or less match their geographical location. It does not look as much like the UK but it gives you a much more immediately accurate impression – that Labour is the current government, that the Conservatives are second and that the Liberal Democrat have just a few scattered seats.

If you wanted someone to use a dashboard, say, where this information was displayed the second map is much more powerful, useful, accurate, speedy etc. In fact, unless you wanted to be able to make snap judgments about distances or geographical areas, the first map is more or less completely unhelpful.

Why, then, do all the map interfaces I see insist on using “real” maps? Mostly companies are not concerned with geography but with things like concentration of consumers, prospects, customers, Fortune 500 companies, new homes etc. Wouldn’t a map interface that made an important factor the basis for sizing regions or territories be more useful? Why does no-one do this? A traditional map gives a false first impression and let’s face it you care about the first impression if you are bothering to use a map in the first place!

So, go right now and ask your favorite BI/dashboard vendor about maps and see if any of them have anything useful to say about cartograms – projections based other than on geography.

And don’t even get me started about the people who still use the Mercator Projection for a world view….