本研究旨在比較日本職棒外籍與本國籍球員在2000-2017年間之投入產出績效。運用資料包絡分析法(Data Envelopment Analysis)，以薪水為投入項，投手產出項為出場數、勝投、防禦率；野手則為全壘打、打點、打擊率，評估外籍與本土野手球員之技術效率，第二階段運用隨機效果的Panel Tobit模型估計選手個人特質如身高、體重、年齡、慣用手對效率的影響。DEA的估計結果顯示：外籍球員效率普遍低於本土球員，此可能導因於外籍球員雖然平均成績好，但薪水過高導致效率較低，存在國籍薪資溢酬的現象。第二階段的迴歸發現，不論投手或野手，年輕的選手與效率為正向關聯：投手部分體重則是負向顯著。外籍球員雖有即戰力的效果，但外籍球員有限制名額，長期看來，培育本土年輕選手除了能讓球團效率提升，對日本職棒的未來發展更有幫助。

This study aims to compare the input and output performance of Japanese professional baseball players and national players between 2000 and 2017. Using Data Envelopment Analysis, the salary is the input, the pitcher output is the number of appearances, the winning vote, the earned run average; the wilderness is the home run, the RBI, the Batting Average, and the evaluation of the foreign and local fielder players. Technical efficiency, the second phase uses the Panel Tobit model of random effects to estimate the individual traits of the player such as height, weight, age, and the influence of the dominant hand on efficiency. The DEA estimates show that the efficiency of foreign players is generally lower than that of local players. This may be due to that foreign players have a good average score, but the salary is too high, resulting in low efficiency and the existence of national salary. The second phase of the regression found that young players are positively associated with efficiency, whether pitchers or field players: the weight of the pitcher is negative. Although foreign players have the effect of fighting strength, foreign players have limited quotas. In the long run, cultivating local young players can improve the efficiency of the team and help the future development of the Japanese professional baseball team.

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