NPR projects winners in contests we are watching by aggregating information from state election authorities, exit polls, reporters in the field and the Associated Press.
In presidential contests, NPR editors confer before calling battleground states for one candidate or another. In congressional contests and gubernatorial races, such as those on ballots today, NPR editors tend to rely more on the analysis provided by the Associated Press.
And in fact tonight, NPR editors will rely in particular on the AP, which monitors all 435 House races, 37 Senate races and 37 gubernatorial races simultaneously and can project winners in multiple states at once.
NPR is not a partner in the consortium that produces data from "exit polls." But we are subscribers to the national poll data and data from a few states as well.
Exit polls provide projections based on interviews with voters chosen at random as they leave polling stations in selected precincts. These polls are scientifically conducted and usually quite accurate when they have been reviewed and adjusted to reflect and balance demographic representation. So their greatest value is in profiling the voters who turned out and describing the issues those voters say motivated them.
They are of some value in projecting winners in some races, but NPR does not project the results of any cases based strictly on exit polls.