本研究採用Granger and Teräsvirta (1993)和Teräsvirta (1994)所提出的平滑移轉模型迴歸檢定方法，自非線性(non-linear)的角度切入探討各對美主要貿易國貿易餘額對於美國總體經濟在美國總貿易餘額多寡不同的情境下所可能產生的不同影響衝擊。樣本區間取樣自2010年第一季至2019年第四季之40筆季資料觀察值。
研究首先得到研究模型設定為指數型平滑移轉自我迴歸(ESTAR)函數模型。另得到美國總貿易餘額數值在-140496.25(單位為百萬美元)呈現為顯著門檻值。進一步觀察分析，發現巴西、OPEC、及日本三個國家或組織對美國總體經濟無論在門檻值左右或偏離門檻值時，都將出現顯著的影響效果，其餘四個解釋變數國家(加拿大、墨西哥、歐盟、中國)之對美貿易餘額則皆呈現不顯著影響。
    研究首先得到研究模型設定為指數型平滑移轉自我迴歸(ESTAR)函數模型。另得到美國總貿易餘額數值在-140496.25(單位為百萬美元)呈現為顯著門檻值。進一步觀察分析，發現巴西、OPEC、及日本三個國家或組織對美國總體經濟無論在門檻值左右或偏離門檻值時，都將出現顯著的影響效果，其餘四個解釋變數國家(加拿大、墨西哥、歐盟、中國)之對美貿易餘額則皆呈現不顯著影響。
  研究進一步分析發現，無論在何種對美之貿易互動數額下，巴西對美貿易會正向衝擊美國之總體經濟，日本則相反的出現無論在何種貿易數額下，對美國總體經濟呈現負向衝擊之影響，且兩國對美貿易在美國對全球貿易數值出現在一千四百億美元左右赤字時，其衝擊影響更為加大。最後，OPEC則出現對美貿易餘額在不同區間下之對於美國總體經濟之不同衝擊影響結果，當美國對全球貿易數值在門檻值一千四百億美元左右赤字時，OPEC對美貿易餘額之對於美國總體經濟呈現正向影響，但當偏離該門檻數值時，則多呈現出負向之衝擊影響。

This paper applies the non-linear methodology of smooth transition autoregressive model (STAR) elaborated by Granger and Teräsvirta (1993) and Teräsvirta (1994) to investigate the effect of the trade balance with each US trading partners on the US economy. The sample period adopted is from 2010Q1 to 2019Q4, which has totally 40 observations.
  The appropriate model is specified as the ESTAR model by our model specification and the threshold value of the US trade balance is significantly found to be -140496.25 million US dollars. This paper further observes that the trade balance of three countries or organizations, Brazil, OPEC and Japan, show significant influence to the US economy. However, the other four countries or organizations (Canada, Mexico, European Union and China) show no significant impact on the US economy.
  The further findings are that Brazil shows positive impact and Japan shows negative impact on the US economy whichever level of the US trade balance is. Moreover, the closer to the threshold value of -140496.25 million US dollars the larger the impact on the US economy for both countries of Brazil and Japan. Nevertheless, OPEC shows different impacts on the US economy around and depart from the threshold value, positively around the threshold value and negatively depart from the threshold value.

目錄	V
表目錄	VI
圖目錄	VII
第一章	緒論 1
第一節	研究背景與動機 1
第二節	研究目的	4
第三節	研究架構與流程 6
第二章	相關理論與文獻回顧 7
第一節	貿易自由化與貿易餘額 7
第二節	匯率變化、貿易條件與貿易餘額 8
第三節	貿易餘額與經濟變數 10
第三章	研究方法	13
第一節	單根檢定法 13
第二節 平滑移轉迴歸模型 18
第四章	實證結果與分析 24
第一節	資料來源與分析 24
第二節　單根檢定	32
第三節　線性檢定	34
第四節　轉換函數檢定 35
第五節　模型之參數估計與檢定 36
第五章	結論與建議 41
參考文獻	43

表目錄
表1-1-1  2011至2019年美國與主要貿易對手國間的貿易餘額統計表 2
表4-1-1  2011至2019年美國貿易餘額統計表 26
表4-1-2  各變數敘述統計量	28
表4-2-1  各變數之單根檢定結果 32
表4-3-1  模型線性檢定及門檻變數最適落階期 34
表4-4-1  轉換函數模型檢定	35
表4-5-1  指數型平滑移轉迴歸(ESTR)函數模型參數估計 37
表4-5-2  對美主要貿易國之對美經濟區間影響 39

圖目錄

圖1-3-1 研究架構與流程 6
圖3-2-1  邏輯型函數圖形 22
圖3-2-2  指數型函數圖形 22
圖4-1-1A 被解釋變數的(季節調整)美國名目GDP 30
圖4-1-1B 門檻變數的(季節調整)美國貿易總餘額走勢圖 30
圖4-1-1C 九個與美國貿易對手國貿易餘額解釋變數的序列走勢圖 31
圖4-5-1  指數型平滑移轉迴歸(ESTR)函數模型參數估計 37
圖4-5-2  美國總體經濟之美國貿易總餘額落期1季ESTR門檻效果圖 38

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