Elo is known for his chess player rating system. The original player rating system was developed in 1950 by
Kenneth Harkness, the Business Manager of the United States Chess Federation. By 1960, using the data developed through the Harkness Rating System, Elo developed his own formula, which had a sound statistical basis and constituted an improvement on the Harkness System. The new rating system was approved and passed at a meeting of the United States Chess Federation in
St. Louis in 1960. In 1970,
FIDE, the World Chess Federation, agreed to adopt the Elo Rating System. From then on until the mid-1980s, Elo himself made the rating calculations. At the time, the computational task was relatively easy because fewer than 2000 players were rated by FIDE. FIDE reassigned the task of managing and computing the ratings to others, excluding Elo. FIDE also added new "Qualification for Rating" rules to its handbook awarding arbitrary ratings (typically in the 2200 range, which is the low end for a chess master) for players who scored at least 50 percent in the games played at selected events, such as named
Chess Olympiads. ==Book==