本文使用兩種資料包絡分析 (data envelopment analysis, DEA) 方法來估計國家生產效率，一為不考慮非意欲產出的生產效率，另 一為考慮二氧化碳的排放量做為非意欲產出計算所得出之生產效 率。我們比較兩種生產效率，發現歐洲國家近年來對環境所投入之 人力、物力已見成效，此與以往相關之文獻結果不同。本研究進一 步採用空間分量迴歸模型來分析影響國家生產效率的因素，本模型 可同時解決資料具空間相關性及異質性的問題，在分析時可避免偏 誤的問題，結果證實此模型之適用性優於傳統迴歸模型。由模型推 估結果發現，若以不計非意欲產出之生產效率做為應變數時，我們 發現低生產效率國家有顯著空間相關性，高生產效率國家則無；貪 腐程度則對高生產效率的國家影響較大，外人直接投資對低效率國 家之影響較為顯著，貿易量則可能對高生產效率的國家有負向的影 響。若以考量非意欲產出之生產效率來看，發現空間相關性仍存在， 惟效率最低的國家將無法透過周邊國家的技術外溢獲得益處；而貪 腐程度對高生產效率國家之負向影響將遠大於低效率的國家，此乃 因為高效率國家之貪腐程度越高將使得二氧化碳排放增加。此外， 最低生產效率的國家將不再經由外人直接投資獲益。最後，我們發 現提高貿易量反而可能引發低效率國家之生產效率降低。

This article uses two types of the DEA (data envelopment analysis) method to estimate the production efficiency of countries: one does not consider undesirable output, and the other one considers carbon dioxide as an undesirable output. By comparing the results from these two types of efficiency estimation, we find that the efforts by European countries in recent years have paid off, which is different from results in the past literature. This study employs a spatial quantile regression model to analyze the factors affecting the efficiency of national production. The model solves the problem of data exhibiting spatial correlation and heterogeneity and therefore avoids biased estimations. We show that the degree of corruption affecting high production efficiency countries is more significant, that foreign direct investment has a significant effect for less efficient countries, and that trade might have a negative impact for highly productive countries. By considering undesirable output, when spatial correlation does exist, the least efficient countries do not get the benefits through technology spillover from adjacent countries. The extent of corruption influences highly productive countries more negatively than inefficient countries, because the high degree of corruption in higher productive countries allows for an increase in carbon dioxide emissions. In addition, the least productive countries no longer benefit from foreign direct investment. Finally, we note that an increase in trade likely leads to lower production efficiency in less efficient countries.