When you see a news outlet “call” the winner of an election, it can feel like official results are in, but these unofficial projections are just forecasts until they are certified by local and state election officials. The process of counting votes and certifying results takes days and sometimes weeks after Election Day to make sure every ballot is securely counted.
Several factors determine whether a race is close enough to warrant a recount. These include the size of the margin between first and second place, the number of early in-person or mail ballots cast before the election and the patterns of past elections. In addition, many states have rules that allow a trailing candidate to request a recount if the final result is within a certain percentage of the vote margin.
The report also examines the real-life impact that a few votes can have. For example, in one legislative race, a single voter’s decision made the difference between preserving affordable health care and ending it.
Vote reporting systems link data sources to track the election and predict the outcome of a race before the polls close. Each media outlet’s system is unique, but most incorporate information like the results of exit polls, the total number of eligible voters and the number of in-person and mail ballots received before the election, partial results collected by reporters as they are released after Election Day, and historical patterns. These data are used to create statistical models that help news outlets estimate the final result. The model is then tested against the full results as they become available to see how well it predicted the actual result.
