Seymour Siwoff, who brought statistical analysis to the sports world, chronicling feats from the epic to the arcane through seven decades as the head of the Elias Sports Bureau, died on Friday at his home in Manhattan. He was 99.

His death was confirmed by his grandson Joe Gilston, whose Joseph Gilston Trust took over Elias in March, purchasing 100 percent of its stock.

Until then, Mr. Siwoff had since 1952 been the president and chief executive of Elias, the official record-keeper for America’s major professional sports leagues. In recent years the bureau’s day-to-day operations had been overseen by Steve Hirdt , the executive director, but Mr. Siwoff remained a presence in its Manhattan office until just a few months ago.

When Mr. Siwoff took control of Elias, it was tallying basic baseball records for newspapers and wire services. At the time, the Brooklyn Dodgers were evidently the only team with its own statistician, Allan Roth , who tracked the performances of the Dodgers’ players.