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Projection primer

We're in the thick of the poll closings and the post-election speeches right now, so it's a good time to review one of the basic questions of the Election Night business, as posed by Hank from Annapolis, Md.:

"How are the projections done? It looks like a lot of them don't match the current leader from the polls. How can you accurately project from 7 percent reported results?"

Actually, projecting the outcome of an election can sound a lot like doing a poll, or predicting the weather. The results may not always be sure-fire (remember the 2000 election?), but we hope that every election cycle brings improvements in the process. Here are a few basics about Election Night terms, gleaned from NBC News' policies:

NBC has two types of winners by the end of election night:

  • Projected winner: NBC has made a projection that a candidate will win the race, but the vote count is not yet complete. This call is made only after all the polls are scheduled to have closed in a state. Projections are based on an analysis of exit polls, precinct models from scientifically selected samples, county vote models using Associated Press data, and the actual raw vote.
  • Apparent winner: A candidate who has won the race when all the votes have been counted but the margin is small enough that the result may change by the official count or a recount.

We're not talking about the "official" winner here. After all, it may take weeks for states to certify the official winner of an election.

During the evening, NBC may report that a race is "too early to call" - meaning there's just not enough data to make an analysis. Or you may hear that it's "too close to call." As you might guess, that means the data are available, but there's not enough of a margin for NBC to feel confident about projecting a winner.

So where do the exit polls and the sample precinct results come from? The source is the National Election Pool, a pool of The Associated Press and the five major TV news networks that was organized for the 2004 election.

For an outside opinion about the projection game, check out this posting from The Caucus at NYTimes.com.