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Can Statistical Analysis Predict the 2010 Midterm?

A note of caution.

1:49 PM, Sep 7, 2010 • By JAY COST
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I think this lack of forward progress is partially due to a combination of several factors: (a) most political variables correlate with one another at least a little bit; (b) there are only a handful of elections; (c) the number of elections in which something "big" happened are fewer still.  Taken together, all this means that the same data can support many different models that specify a whole range of theories about how congressional elections really work.  Each model will predict the past with accuracy, and will often point toward different future results than its competitors.  Unfortunately, the same situation that produces a multiplicity of competing models makes it very hard to eliminate "wrong" ones.  It’s easy to tweak models to fit the most recent data, and so the number of potentially correct statistical models never seems to get smaller.

That does not seem like a good scientific process to me.  Instead, it seems to me like a situation in which good scientists lack sufficient data to distinctively specify and conclusively test their theories.  

The reason I am writing about this on a non-technical page is that statistical analysis implicitly possesses clout because of its technical nature.  It’s hard for non-experts to evaluate this kind of wonkish material for themselves, and that can result in an appeal to authority that I don’t think is appropriate.  I’d advise caution and care in evaluating these predictive models.

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