8900 people. That's all it took to make one of the best maps available of Belgium. (*1)
I don't believe there's a decent way to count labour hours, but here's a rough number: 61 labour years, assuming 200 days worked a year, 8 hours a day (*2). Considering Belgian labour prices, I'd guess that represents at least 3.000.000 euros.
I started doing these statistics after someone assumed that the southern/Francophone part of Belgium was underrepresented in Belgium. There's nothing as fun as being able to check these things. Some numbers I published before: it looks like the Dutch speaking part is mapped in more detail.
But the best simple proxy of map quality seems to be contributor density. So where are the contributors at?
Well, they're in Flanders.
It would be silly to stop there: there are more people in Flanders. You could divide them by area, but I believe the amount of data needed to map something is more dependent on people than on space. The Sahara is quite large, but you'll never need as much data to map it as you would for little old Belgium. So here's the same graph, in contributors per million inhabitants:
And there you go: the Flemish are the laggards, Brussels and Wallonia lead. This is really counter intuitive. I started out ignoring this, but it kept nagging in the back of my head. Remember how data density is higher in Flanders.
Then I thought about how one of the most productive mappers in the world lives in Flanders. So what would happen if we just exclude this one guy?
Turns out 44% of all nodes in Flanders were mapped by one person. In Brussels too there is one person who added about 30% of all nodes. Wallonia simply doesn't have someone like this, with the top contributor adding "just" 10% of all nodes. So I made the same graph, but without the number one contributor in each region.
Suddenly, we're all the same. Try and make our politicians believe that!
So that goes to show that even in a densely mapped country like Belgium, one person can still make all the difference.
That takes us back to basic community statistics in Belgium. Here's the number of active contributors per year per region. The bumps in the curve in Brussels are probably because of the small size of the region - just over a million inhabitants.
If we take into account people with at least 5 sessions (active on at least five different days in a year), the numbers drop steeply. Wallonia is clearly number one here, with Brussels and Flanders quite a bit lower.
When it comes to recruiting new mappers, Flanders comes in last.
Do people cross borders? Well yes. To define "home", I first took a subset of people with at least fives sessions in Belgium over all years. Then I simply looked at the region they had most sessions in. Of course, you will have some foreign people this way. It leaves us with 83 Brussels mappers, 995 in Flanders and 675 in Wallonia. Of the Brussels mappers, fully 60% mapped at least 10% of the time across the border. Pretty logical of course, because it's small. Only 18% didn't ever cross over. In Flanders, the numbers are 28% and 50%. In Wallonia a similar 25% and 56%.
I've been working towards creating these kinds of numbers for all regions in the world and dump them into a statistical platform. It'll be some time till I can realize that...
Here's a link to some of the data I used
*1. Well, actually, a bit more by now: I used the history dump of january 2015.
*2. I counted every active day per user as one labour hour. It's just a number I made up. You can make up your own if you want. The number of sessions (total number of active days of all contributors) is 97.270.