Thursday, November 19, 2009

Census data and mapping

I attended a Statistical Liaison Officer meeting this afternoon, and forgot the camera, doh. There is nothing particularly interesting about a bunch of us sitting in a room looking at Powerpoint presentations anyway, but the venue is at the beach and very pretty.

These meetings are put on by the Office of Economic and Statistical Research (Queensland State Government) and the Australian Bureau of Statistics (Federal Government). When I first started going to these meetings several years ago I knew nothing about demographic data, and it has been very educational to listen to people talk about the census and other projects to collect data about people, and the issues that arise and how to solve problems.

Coming from a science background I was very ignorant about census data, so it has been a great help that the Government has been so proactive in getting people together and working as a group to educate and share ideas.

I have also had to accept that demographers are not as interested in the maps as they are in the data, and choropleth maps using a default colour ramp is the bog standard way of doing things. I find it boring and repetitive. This is not something I have researched, but surely there are better and more interesting ways of doing it.

I like the colour schemes used in Cynthia Brewers guide to census mapping for the colour vision impaired, at least they look fresh and attractive. (see the online colour brewer application, but be prepared to wait while it loads...here) .

Personally, because the census geography around here is so variable in size, I prefer to use graduated symbols. They are more fun (you can chose something that is meaningful, like a dollar sign for income) and they don't create the visual bias you get from a huge polygon (because of low population) overwhelming small polygons because it is a strong color and dominates the map. It also lets large geographic areas (usually the hinterlands around the edges) be truncated by the neatline and the symbol placed in a more visually comparable area near the other polygons.

I am at home now, and I don't have examples to post. A blog about mapping with no pictures is pretty lame, sorry. You can play with Queensland data here, no map making though! Try the map stats at the ABS for that. I confess I haven't played with these websites before, I get the data and use it in my GIS.

I haven't had the chance to work on a demographic atlas yet, but I can see there is a lot of interesting work to be done. Maybe I will give the City Council a nudge to let me help them with the population atlas they mentioned at the meeting today. It would be very interesting and quite fun. So many things to map, and so little time!

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