January 29, 2013

A Lesson In Selective Evidence

This sentence, by the highly esteemed and very serious George Will was published by both the Pittsburgh Post-Gazette and the Tribune-Review this week:
[President Obama] says "the threat of climate change" is apparent in "raging fires," "crippling drought" and "more powerful storms." Are fires raging now more than ever? (There were a third fewer U.S. wildfires in 2012 than in 2006.)
Tamino debunk's Will pretty well:
Here’s a clue for those who want to know the truth of the matter rather than George Will’s “spin.” When you hear a phrase like “a third fewer U.S. wildfires in 2012 than in 2006,” you know you’re being played for a sucker.
And then there's an explanation:
...comparing this year to a single year from the past — and a cherry-picked one at that — is either dishonest, amazingly stupid, or both. You make the call.

According to the National Interagency Fire Center (NIFC), there were 96,385 wildland fires in 2006 but only 67,315 in 2012 (through Dec. 20th). The 2012 count is less by 30.1%, which is close enough to a third, I’ve got no complaint about that.
But them Tamino raises the issue of number of wildfires vs number of acres burned in those wildfires and concludes that it's the number of acres that's important.

Then we're given a chart:
See that dot that's the highest on the chart?  That's 2006.  The last dot on the right is 2012 and the red line is the upward trend of the data.

Notice something?  That last dot looks to be the third highest of all of them.

Are wildfires getting worse or not?  Once you've answered that, go back and look at how Will framed the issue.

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