(Editor’s note – Continuing our series of getting cartographers to publicly criticize themselves, we next feature Mr. Andy Woodruff, proprietor of Cartogrammar and an alumnus of the famed University of Wisconsin Cartography Lab. If you’re interested in following the brave example of Mr. Woodruff, and Mr. Reynolds before him, and showing the world some of your own cartastrophes, please write me at email@example.com. — DH)
Animated maps can be a delightfully cartastrophic realm, rife with dizzying excessive motion, poorly or over-designed interfaces, annoying sound effects, and (I really, really hope) perhaps a few dancing bananas. Daniel will perhaps be wise to steer clear of them here unless he is willing to give up the rest of his life to unearthing all the bad animated cartography on the internet. With this post I will only lead this blog to test the waters gingerly.
This is a map I completed for a class called Animated and Web-based Maps, instructed by Professor Mark Harrower, the king of cartography at the University of Wisconsin-Madison, and, I should add, a known expert in map animation. It’s animated, sure, and you can click the image to load and play it, but that’s not entirely necessary for what follows. Very briefly, a bit of background on the map: it was made for a lab assignment in which students were provided with a set of county-level agricultural data for the state of Wisconsin for the years 1970 to 1999 and instructed to make an animated choropleth map of a variable of their choosing.
Typically, my first reaction to viewing this map is to vomit at the sight of the colors. Unlike many of the maps that make their way onto this site, mind you, I actually used an appropriate color scheme: a diverging scheme using official Cindy Brewer ColorBrewer specs (and it’s even colorblind-friendly!). But this red-blue scheme combined with the interface color pair of green and more disgusting green… well, I hope you’re reading this on an empty stomach. Otherwise I probably owe you a new keyboard. Oh, and if your eyes aren’t completely filled with blood yet, you just might discern in the background the ghost of a photo I took in Wisconsin’s Driftless Area.
But chalk all that up to bad taste. On to the actual cartographic crimes.
First, the white color in the classification scheme, labeled “0% or No Data.” Hold on a second, 2006 self, there’s a big difference between those two! Zero is a legitimate data value that fits in the classification scheme. “No Data” is a different animal entirely. Ideally one would avoid an incomplete data set in the first place, but sometimes that’s what you’ve got (like when that’s the data provided for the assignment). In those cases, areas without data can’t be indistinguishable from areas with data, or else the map reader can never really know what’s going on. Look at the screenshot: which counties have no data, and which have a value of zero? Impossible to know. In reality perhaps some of those counties should be off-the-charts red, but you’d never know which ones. The counties without data need to be shaded with a color that is not in the map’s color scheme, probably some kind of gray. Worse, in the image above there is in fact only one county with no data, but guess what the tooltip says when you mouse over it. That’s right, “0%.”
Next, two points about the choice of variable to map, beginning with the description I wrote near the legend:
“This map shows the change in the percent of land in farms over the preceding year in each Wisconsin county from 1970 to 1999. This is a percent change of a percent– for example, a change from 50% land in farms to 48% would be shown on the map as a -4% change ( 48 is 96% of 50), not a 2% change.”
It’s as though I deliberately chose the most complicated variable possible, probably in an effort to confuse the TA into giving me a good grade. Though I clearly realized the potential confusion (hence the descriptive example), what I didn’t even think about until now is that the exact same thing could have been mapped without any of the “percent of a percent” nonsense. The percent of land in farms for a given year is the total land area in farms divided by the total land area of the county. The percent change that I mapped is that percent for the first year minus the percent for the next year, divided by the percent for the first year. But ignoring, say, erosion on the lakeshores (and I’m sure this data set did ignore it), the total land area doesn’t change from year to year. So total land area magically cancels out of the whole equation, and it would be mathematically equivalent, and a lot clearer to the reader, to simply show the percent change in agricultural land area. I haven’t taken a math class since high school, and maybe it’s starting to show.
Beyond that, out of all the options this choice seems like a particularly strange thing to map in an animation. The whole purpose of an animated map is to show change over time. But the data are already showing change, so now we’re dealing with change in change. Watch the animation; do you get anything out of it? I sure don’t. Yes, you can see that some years are calm and some are not, but it is very difficult to get a sense of the overall trend of what’s going on with farmland in Wisconsin. It would have been a lot clearer to just map the percent of land in agriculture and watch how that changed over thirty years. Now, this point is debatable because animating change maps is not unheard of. I’ve been told that some important minds and beards have investigated such animation. It can be useful for highlighting or discovering areas of instability. For general-purpose maps such as this one, however, mapping a change variable is best left to single, static instances. If I had animated just the percent of land in farms, the same trends could have been discerned through the animation, and the user would also actually learn something about the amount of agricultural land. A more appropriate use for the change map might have been a single map showing the change over the thirty year span. In fact, the subtitle here, “Change in percent land in farms 1970-1999″ could be realized by that single map.
For a final quarrel, I would argue that the counties on this map should have been labeled. There is ample space, and whereas you might get away with not labeling states in a US map, few people know Wisconsin’s 72 counties by heart. Instead of labels on the map, I forced the user to move the mouse cursor over a county to see what its name is. The rule by which I now try to abide is: don’t lean on interactivity to solve all cartographic challenges. Interactivity as a means to reveal data is a good way to add lots of additional information to a map, but it can also make it easy to be lazy. Laziness is for the map reader, not the map maker. If the information is useful and can be accommodated without relying on interaction, then do it. The specific data value you see when hovering over a county is a good use of interactivity for extra information; the county name is not. It’d be a lot less work to visually scan persistent labels that are sitting there on the map than it is to mouse over counties to see their names one at a time.
And an extra special bonus typographic nitpick: I misused hyphens in place of both an en and an em dash in the subtitle and description, respectively.
One Nice Thing: The animated and interactive features of the map are nearly—but not quite—unbreakable. I won’t mention the one bug I did find recently.