How the AP analyzed football players' weight gain

For a sport with rabid fans, historic rivalries and trivia buffs, college football does not have a single, official repository of historic rosters. Each school prints its own rosters and is responsible for its archives.

To analyze changes in weight over time, The Associated Press obtained official rosters from 2001 to 2012 from all 120 Football Bowl Subdivision schools, the big-time teams that make up what used to be known as Division I-A. School rosters have been recognized by peer-reviewed scientific journals as a legitimate source for studying athletes.