本研究使用資料包絡分析法衡量NBA球員之績效值，並探討球員在簽訂複數年合約前後與績效之關聯性，是否有Stiroh(2002)提出之合約年效應，並進而比較NBA官方提供績效值與DEA法計算出之球員績效值何者對於球員薪資具有較佳的解釋能力。
本研究取用2000年至2011年共11年間曾經歷合約到期並再次向球團簽訂複數年合約的184名球員做為樣本；實證結果發現，在控制年齡、年資、提前續約與否、球員位置及先發球員與否後整體技術效率方面及球員每分鐘平均績效值顯示在球員簽約前績效有顯著提高之現象； NBA官方提供績效值與純技術效率簽約前後係數也是負的，雖然未達到統計上顯著水準，因此，本研究結果顯示NBA球員在簽約新約前的確有合約週期現象，亦即為爭取較佳合約球員在簽約前會刻意表現較佳之績效。
此外，根據Vuong Test比較NBA官方提供績效值與DEA法計算出之績效值和球員每分鐘績效值與薪資關聯性的測試結果，顯示由官方提供之績效值對薪資關聯性較高，說明目前NBA官方提供之績效值仍然是球團用來與球員薪資的談判重要參考指標之一。

The research applies Data Envelopment Analysis to examine the NBA players’ efficiency performance before and after signing a new multi-year contract, and whether there exists the Contract Cycle Effect that suggested by Stiroh (2002). The research also tries to compare NBA efficiency score and DEA efficiency score to test which has a higher association with salary.
The samples selected 184 NBA players who signed a new multi-year contract from 2000 to 2011. After controlling the players’ age, seniority, extension, position and starting or not, the empirical results denote that DEA total efficiency score and the NBA efficiency per minute indicate a higher efficiency score before signing a new contract, The NBA official efficiency score and DEA technical efficiency score also reveal a negative coefficient before and after new contract singed, although the statistical test didn’t reach the significant level. The results imply that NBA players do exist the Contract Cycle Effect phenomenon that players will perform better efficiency in order to get a better contract.
The Vuong test results reveal that the official NBA efficiency score has a higher association with salary comparing with DEA efficiency score. The finding suggests that the official efficiency score is one of the major references for the NBA teams on salary arbitration.

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