We did it! (again)

Anyone living in the current millennium who is even moderately engaged in the politics of our time receives a daily onslaught of political email. Most of this is designed to stoke our outrage at the latest unspeakable act by the other side, and beseech us to send just a few dollars to answer this assault on all that is good. And sometimes the messages exhort us to send our money so that we can show that our side is collecting the most money, and must therefore be most in tune with the public. And if we have done as we are told, at the end of the fundraising cycle, we may get a message with the exhultant cry: “We won!” As if the real battle was over fundraising, rather than the deficit, health care, two wars, or financial regulation.

These messages annoy me somewhat, but nothing sends me into apoplexy like a bad graph. But the latest missive had a doozy: a graph that should shame the artist into permanent retirement from the field of graphology.

Behold Exhibit A: a graph that purports to show the fundraising results for Democratic and Republican groups in the last fundraising cycle. And as the DCCC says: “We did it!”

The numbers tell one tale: evidently $4.4M for the dems and a measly $3.0M for their opponents.

But there is something a bit weird about this picture. The blue bit seems out of proportion. As a professional graphologist (don’t try this at home) I quickly noted one obvious possible source of distortion: the width of the bars. Why is the blue bar wider? Are they using area to represent the number of dollars? That would be ok, though I have my doubts about our ability to judge relative areas. But when I took out my digital ruler, I discovered to my amazement (not!) that the areas were not in the ratio of 4.4/3 = 1.47, but instead in the ratio 2.54! Yes that’s right, the blue rectangle has 2.54 times the area of the red rectangle. If area were accurately representing dollars, then the NRCC would only have raised only $1.73M, not $3.0M. The red area is off by 73%!

Ok, I thought, so the increased width of the blue rectangle is just some sort of rhetorical flourish. It must be the height that represents the two quantities. Again, amazement overcame me. The heights are wrong too! The blue is 1.72 times higher than the red, rather than 1.47 as it should be.

In other words, the only thing the artist got right was that the DCCC got more dollars than the NRCC. For this, we need a graph?

Ok, so what would the correct graph look like? Assuming we use height to represent dollars, here it is. We put some numbers on the axis to make it clear that zero is included.

So, we come to the end of our sad tale. What is the lesson? Simple: if you are going to use a graph to represent numbers, make sure it actually represents the numbers.

Reference:

Email of March 8, 2011, from Rep. Steve Israel, DCCC Chairman <dccc@dccc.org>.

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