The Keys are based on the theory that presidential election results turn primarily on the performance of the party controlling the White House and that campaigning by challenging an incumbent-party candidates will have no impact on results.
Through the application of pattern recognition methodology used in geophysics to data for American presidential elections from 1860 (the first election with a four-year record of competition between Republicans and Democrats) Lichtman and Keilis-Borok developed 13 diagnostic questions that are stated as propositions that favor reelection of the incumbent party.