(1)近十幾年來，一些研究人員開始注意到所得不平等度與地下經濟規模二者之間的關係。其中一些人通過OLS模型考察了世界範圍內地下經濟規模對於所得不平等度的影響。然而，由於各國存在著一些不可觀察到個體效應，加上內生性（雙向因果關係），他們的估計結果可能存在著偏誤。本文應用了從1999年到2005年，83個國家的面板數據，并採用了固定效果模型和GMM模型來克服上述缺陷。本文的主要發現是，地下經濟規模對於所得不平等度有著正向顯著的影響——特別是在開發中國家中。
(2) 地下經濟是世界範圍內重要的經濟現象，其存在對於公部門征收財稅的能力有一定的影響。因而，理解地下經濟形成及變化的原因，有助於政府制定出更加合理的政策來降低地下經濟的規模，從而增加征稅能力。本文研究了台灣的地下經濟情況，並使用了OLS和VAR兩種計量方法來估計不同種類的稅收以及其他變數對於台灣地下經濟規模的作用。結果顯示，營業稅有著正向顯著的效果。因而政府可以考慮通過調降營業稅的稅率來降低地下經濟的規模，因為這樣做能夠以最小的成本來縮減給定程度的地下經濟。

(1)Recently a few studies focus on the relationship between income inequality and the shadow economy and some explore the impact of the shadow economy on income inequality based on OLS regressions. However, the non-observed country-specific effect and potential endogeneity may cause the results to be biased. This paper utilizes panel data from 1999 to 2005 for at most 83 countries and employ fixed effect model and GMM method to overcome this shortcoming. The main finding is the shadow economy has a significantly positive effect on income inequality, especially in developing countries.
(2)Shadow economy is a worldwide important economic phenomenon affecting public sectors’ abilities to collect fiscal resources. Understanding the causes of shadow economy could help the government make reasonable policy to reduce the size of shadow economy and then improve the capacity of tax collection. This paper focuses on Taiwan’s case and employs both standard OLS and VAR model to estimate the impacts of various kinds of specific taxes and other variables on Taiwan’s shadow economy. The results show that business tax has significant positive effect, which implies that a government should consider a business tax reduction to reduce the size of shadow economy because this way is least costly.

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