Friday, June 08, 2007

75% of Americans Favor 40 mpg by 2010? Really?

Reading the press release linked below about a completely flawed survey just lit a fuse inside me. The spirit moved me to write:

75% of Americans Favor 40 mpg by 2010? Really?

By Chris Haak


On Wednesday, an organization called the Civil Society institute, which advocates a 40 miles per gallon CAFE standard for US vehicles by 2010, issued a press release that has been picked up by a few news outlets. Here is a link to the press release.

They claim that an overwhelming majority of Americans favor a more radical increase in the CAFE fuel economy standards than even Congress is pushing for; based on a “scientific survey” that they sponsored. I was dubious of these claims, so I dug a little further. Before I even get into the flaws in their specific survey, let’s think about a few things.

The formal report has confidence intervals and all sorts of fancy statistical justifications, but the fact is, the questions are terrible. You can have the best sample of respondents in the world, but if your questions have an inherent bias or flaw, then your survey is flawed. They also don’t say whether the survey companies identified themselves as representing an organization that advocates 40 mpg fuel economy standards by 2010, but the tone of the questions makes it clear to the respondent thinks the question wants them to have.

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