The closing narrative of the McCain campaign is apparently going to be “Obama’s a pinko commie socialist who wants to raise your taxes,” which means it’s time for all good liberals to bust out the graphs to show why this is false. Well, graph, singular. You know the one:
I don’t remember who first posted it (I got it here), but it’s been everywhere this campaign. It shows a head-to-head comparison of the consequences of the McCain and Obama tax plans for various income groups.
I hate this graphic.
Not because of the information it contains, mind– that’s fine. I hate this graph because it does such a terrible job of presenting the information it contains.
I’m not just talking about the fact that it blindly uses all the idiotic default settings of Microsoft Excel (well, ok, it doesn’t have the dark-grey background, but it’s got all the rest). This is a graph that only a policy wonk could love.
First of all, what’s being plotted? The axis labels don’t really help– “Percent” is only slightly more illuminating than “Y Data.” You need to look up at the title to find that it’s “Average Percentage Change in After-Tax Income, 2009.” Not only is that information that needs to be on the graph itself, not just in the title, it’s a confusing quantity to plot.
I understand why they did it that way– you’d need a log scale to plot the absolute dollar values and keep everything visible, but you can’t do that since the quantity changes sign for Obama. Still, this is a terrible variable for making your point. “Average Percentage Change in After-Tax Income” is not an intuitively obvious thing– the average person does not have a terribly good grasp of percentages. It also tends to understate the hugeness of the difference at the high end, because you’re taking percentages of larger values.
The horizontal axis is even worse. The first five bars represent the five income quintiles. Two quick questions, and no fair Googling:
- What’s a quintile?
- What incomes fall in the third quintile for the United States?
Actuaries and policy wonks may think in income quintiles, but this is not a common quantity. The average voter is not going to grasp this concept– something like 20% of people famously think their income is in the top 1% (though some people challenge that statement). Adding the bars for the top 1% and top 0.1% don’t really help, either.
So, basically, the graph-maker has plotted confusion as a function of obfuscation. The graph shows a percentage change in income, which most people won’t understand very well, plotted as a function of income quintile, which most people won’t understand at all.
All this graph really gets you is “The bars get bigger at the high end, and Obama’s bars go negative.” This works wonderfully with people who have a realistic idea of where to locate themselves on the horizontal axis, but it’s a dismal failure otherwise. For a lot of under-informed voters, it probably plays right into the McCain narrative, as people will say “Well, I’m middle-class, so I must be in the middle, maybe a bit above, and hey! Obama’s going to raise my taxes!”
There is a vastly better version of the same graph floating around (I found it here):
This is much more like it, and not just because it avoid Excel’s dreadful aesthetic. It’s the same information, but it turns the graph on end, and gives actual numbers for all the important quantities. The income ranges are defined by top and bottom incomes within each range, so there’s no room for confusion about where a given voter should fall. There are bars showing the percentage change for each group, but also boxes giving the absolute dollar value of the average tax change.
This graph lays out the difference even more starkly. The difference between plans for millionaires is almost $1,000,000 (a big increase from Obama, a big cut from McCain), while the difference between tax plans for someone right in the middle of the middle class is about $700 in Obama’s favor.
This is how you present the relevant information properly. The dreadful Excel chart up top is fine for preaching to the liberal choir, but won’t do anything but confuse an undecided voter.