Journal of the Korean Data and Information Science Society

The Korean Data and Information Science Society (한국데이터정보과학회)
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Measuring the accuracy of the Pythagorean theorem in Korean pro-baseball

한국프로야구에서의 피타고라스 정리의 정확도 측정

  • Lee, Jangtaek (Department of Applied Statistics, Dankook University)
  • Received : 2015.03.16
  • Accepted : 2015.04.10
  • Published : 2015.05.31
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Abstract

The Pythagorean formula for baseball postulated by James (1982) indicates the winning percentage as a function of runs scored and runs allowed. However sometimes, the Pythagorean formula gives a less accurate estimate of winning percentage. We use the records of team vs team historic win loss records of Korean professional baseball clubs season from 2005 and 2014. Using assumption that the difference between winning percentage and pythagorean expectation are affected by unusual distribution of runs scored and allowed, we suppose that difference depends on mean, standard deviation, and coefficient of variation of runs scored per game and runs allowed per game, respectively. In conclusion, the discrepancy is mainly related to the coefficient of variation and standard deviation for run allowed per game regardless of run scored per game.

야구의 피타고라스 정리는 야구의 승률을 추정하는 방법으로 오랜 기간 동안 타당성이 입증되고 또 활용되고 있다. 본 연구에서는 2005년부터 2014년 사이의 한국프로야구 팀대 팀 전체기록을 이용하여 실제승률과 피타고라스 정리에 의해 추정된 기대승률의 차이가 발생하는 원인을 회귀모형을 이용하여 살펴보았다. 기대승률과 실제승률의 차이가 큰 경우는 득점과 실점의 분포가 특이하다는 가정아래에서 종속변수는 실제승률과 기대승률의 차이, 독립변수로는 게임당 득점 및 실점의 평균, 표준편차, 변동계수를 각각 이용하였다. 그 결과 실제승률과 기대승률의 차이에는 게임당 실점의 표준편차와 변동계수가 영향을 미치며 게임당 득점의 영향은 없는 것으로 나타났다.

Keywords

References

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