新手與老鳥選手的好球帶差異

Differences of strike zone between juniors and seniors

林昱丞(Yu-Cheng Lin)

指導教授 ： 林明仁

國立臺灣大學/社會科學院/經濟學研究所/碩士(2021年)

https://doi.org/10.6342/NTU202103657

摘要

裁判的公正決策對於職業棒球大聯盟 (MLB)等職業體育聯盟至關重要。然而研究顯示，棒球比賽裁判的偏誤判決可能是由多種原因造成的，例如:種族不同、明星球員和主場，但很少有研究判決偏差是因球員還是菜鳥而導致的。本文的目標就是檢驗這種偏見存不存在於MLB。我們根據 2015-2018 年美國職棒大聯盟常規賽季的每一球資料（超過 1,000,000筆資料），去刻畫出了好球帶，然後使用線性機率模型，probit 模型與logit 模型。在控制了其他變數後，我們發現裁判的確有判決偏差在好球帶的邊上，且此偏差對於新人打者及新人投手都是有害的。雖然我們的數據無法控制投手和捕手的組合，但我們至少控制了其他變數，提供新的想法給未來這方面的研究。

關鍵字

運動經濟學 ； 棒球 ； 好球帶差異 ； 菜鳥 ； 裁判偏見

並列摘要

Unbiased decision making by judges is crucial to professional sports league such as Major League Baseball(MLB). However, researches have shown that biases from umpires of baseball games can caused by many reasons, such as races, star player and home team. But few studies are related biases due to lack of experience. We aim to investigate potential junior biases by MLB umpires. We do so in the context of the subjective decision as to whether a pitch is called a strike or a ball, using pitch by pitch data from the 2015-2018 MLB regular seasons, which is over 1,000,000 observations. We used linear probability model ,probit model and logit model. Controlling for the other effects influencing umpires and for what situation in baseball games in the model, we found small biases near the edge of strike zone. Those biases were all harming junior players, for instance: having more probability to call strike for junior batters, or having less probability to call strike for junior pitchers. The statistically significant differences of probability suggest that there do exist bias due to lack of experience from umpires. Although our data is short of identifying the pitcher and catcher combination, we at least identify other effects and have a new idea for future works.

並列關鍵字

Sport economics ； Baseball ； Differences of strike zone ； Rookie ； Umpire biases

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