Annals of Bad Graphs: DC Heat Wave

by John Sides on July 2, 2010 · 3 comments

in Uncategorized

The speculation is over, it’s official. Even with a somewhat chilled final day of the month, June 2010 finished as the warmest on record for both D.C. and Dulles.

That is the point of this post at the Washington Post’s weather blog. How do they illustrate this fact? With this abominable graph:

wapojunetemps.PNG

Which is captioned:

The top 15 warmest Junes on record since 1871 in Washington, D.C. 2010 set a new record by a significant margin.

Where to begin? The Excel defaults. The weird choice of putting ranked data on a horizontal graph than a vertical column. The fact that the most recent year ends up being on the lefthand side, when the eye is used to “reading time” left to right. I’m sure there are more flaws than these.

More the point, why not just show all the data? Here is my attempt at a graph, with a smoothed trend line included.

dcjunetemps.png

{ 3 comments }

Seth July 2, 2010 at 12:38 pm

Nice graph, although I might quibble with the title. My great great granddaddy flew into Reagan National back in the sweltering summer of 1874. It was so hot, his steam-powered iPad exploded.

Vox Octopi July 2, 2010 at 2:04 pm

Their graph is perfect fodder for the “MSM has a left-wing bias” crowd. I’d blame it on ulterior motives if I wasn’t so sure it was incompetence.

LFC July 4, 2010 at 12:35 pm

Your graph is better than the Post’s, but I don’t think the Post’s is that bad. Your criticism re “putting ranked data on a horizontal graph rather than a vertical column” doesn’t entirely convince me, since the Post’s graph is a series of (vertical) columns which seem to convey info adequately, if not as informatively as yours does.

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