出塁率
On-base percentage is calculable for professional teams dating back to the first year of National Association of Professional Base Ball Players competition in 1871, due to the component values of its formula being recorded in box scores of the time. However, the statistic was not conceptualized until sometime in the late 1940s by Brooklyn Dodgers team statistician Allan Roth, in consultation with then-Dodgers general manager Branch Rickey. In 1954, Rickey, who was then the general manager of the Pittsburgh Pirates, was featured in a Life Magazine graphic in which the formula for on-base percentage was shown as the first component of an all-encompassing "offense" equation. However, it was not named as on-base percentage, and there is little evidence that Roth's statistic was taken seriously at the time by the baseball community at large.