Cheaper by the Dozen, is a book by Frank Bunker Gilbreth, Jr. and Ernestine Gilbreth Carey that tells the story of motion study experts Frank Bunker Gilbreth and Lillian Moller Gilbreth, and their twelve children. The title comes from one of Gilbreth's favorite jokes: it often happened that when he and it family were out driving and stopped at a red light, a pedestrian would ask "Hey, Mister! How come you got so many kids?" Gilbreth would pretend to ponder the question carefully, and then, just as the light turned green, would say "Well, they come cheaper by the dozen, you know," and drive off.
Other humorous incidents recounted in the book include a neighbor campaigning for birth control, who was flabbergasted when all twelve children lined up on signal, and a motion study of tonsillectomy which produced no results because the photographer forgot to remove the lens cap.
Cheaper by the Dozen was made into a 1950 motion picture starring Clifton Webb and Myrna Loy as Frank and Lillian Gilbreth.
Cheaper by the Dozen (2003) was also made into a comedy movie about the Gilbreth family.
