Thank you for the reply and for showing me some samples of what a 2008 US election map with a gradient instead of plain colors for parties would look like.

I guess you are right, as more data is added to the map, it makes the map harder to read and understand, although it’s more accurate.

I did do some versions of the election map with a continuous blue-red color scheme, but for that original poster we opted for the clarity of the two-color scheme. Here’s one with the shades of purple (it should be surrounded by a black background according to our rules, but this was before we made the rules).

That one could use some tweaking to bring out the colors better, but regardless I think all the colors do make it rather difficult to read correctly, even if it is more accurate. Of course that’s one of the big limitations of this technique, and why we officially advised using only a few colors on a map.

Several other variations on the election map are here: http://www.axismaps.com/blog/2008/12/election-map-follow-up/

I am not an expert on maps or anything, I just like maps and occasionally create maps as a hobby.

I must say that the mapping technique (Value-by-Alpha Map) that I read about here is very interesting.

However I would like to point out one suggestion. The map (2008 US elections) shows only 2 aspects out of 3, which I think are the most important here.

The aspects shown on the map are obviously the winning party (represented by red or blue) and the population of the county (represented by the brightness of the color).

A 3rd, and important aspect which I think is omitted is the amount of votes for each party.
I mean, it’s not the same to label as blue or red a 51% vs 49% win and also a 95% vs 5% win.

This aspect could be shown on the map by gradients between 100 percent blue and 100 percent red instead of just plain red or blue.

For example if blue had 75% and red 25% then it would be a shade of purple, closer to blue than to red. This color would then be affected by the population layer, which would change its brightness.

It would be interesting to see if such a map is easier to read and understand or it’s just too cluttered and therefore hard to read.

Of course there might be other factors, such as only a fraction of the population of a county voted, which might be taken into account.

What do you think?

Animation is of course another important thing to consider, as is interactivity. There are plenty of unanswered questions about static versions, but if this technique can pass tests there it may be worth doing some comparisons with animated and interactive versions. I’m not sure how much research has been done with animated cartograms, actually. I know I’ve at least seen some work with animated Dorling cartograms before. You may know more, Alex, and if either Rob or Zach happen by here they would probably know some background on that subject.

I created this – animated dorling cartogram of unemployment over three decades – I think it does a reasonable job of representing the ebb and flow..

http://www.datadrivenconsulting.com/2010/05/dorling-cartogram-of-unemployment-1980-2009/

Ian