Exit Polls

Having gone over the concept of sample size, it's interesting to turn to one of the most well-known samplings: election exit polls. Who does these exit polls and how are they performed?

As it turns out, ABC, Associated Press, CBS, CNN, Fox and NBC formed a consortium in 2003 called the National Election Pool (NEP). NEP then contracted with Edison/Mitofsky to conduct exit polls across the country and provide analysis and projections.

According to the latest news on the Edison/Mitofsky site, they sampled 2300 voters (1442 democrats and 880 republicans) in yesterday's Wisconsin primary. You can find the details of all the Wisconsin exit poll questions at CNN's web site.

The Milwaukee Journal Sentinal reports the details of the actual vote count broken down by county and congressional district for both the Democratic and Republican primaries. The total number of reported voters is about 1,515,630 (1,108,119 democrats and 407,511 republican) .

On the democratic side, the exit polls showed Obama had 57.1% of the votes and Clinton had 42.0%. In the final tally, Obama beat Clinton 58% to 41%. It turns out that the exit polls were accurate within about 1% or 15,000 votes.