During election night,. you can be certain that every network will, at some point or another, call a race for a candidate. How do they decide when to call it, and who to call it for?

That is where Sheldon “Shelly” Gawiser comes in.

Gawiser, a former college professor, is the director of NBC News elections, and oversees the Decision Desk, a group of NBC staffers who are charged with analyzing the data, crunching the nmbers and deciding when to call a particular race.

Every network has a similar group of people, usually isolated from their broadcast colleagues so as not to affect their decision-making.

After the jump, Gawiser explains what viewers can expect on election night.

(H/T NBCU Direct)