自2008年的金融海嘯後，黃金市場吸引著來自全球的投資者投入資金進行避險，當投資者進行投資組合規劃時，美元兌歐元的匯率變動和油價變化也深深影響著全球資金的流動和金融市場。因此在此篇論文的第一個研究議題上，以門檻效果的STAR模型來探討黃金價格、油價及匯率的非線性關係，實證結果發現以匯率做為門檻變數時，三個變數的關係為LSTAR模型，而以油價為門檻變數時，則是ESTAR模型，不論是在LSTAR和ESTAR模型，金價與匯率均存在著較大的門檻效果。 而在第二和第三的研究議題上，我們採用縱橫平滑轉換模型(PSTR)來分析石油出口國及進口國在油價與私人消費上的門檻效果，因為考量到消費者在油價上漲時會產生遞延消費的現象，因此以落後一期的油價做為門檻變數。實證結果顯示，當門檻變數落入低和高區間時，石油出口國的消費者會減少其消費支出；相反地，在石油進口國的實證結果中發現，當門檻變數落入中間的區間時，消費者會減少其消費支出。 In recent years, gold markets have attracted considerable attention from investors, because it is used as hedge to fight the increasing risk after the financial crisis of 2008. The exchange rate of the dollar/euro is interchangeably used in investment portfolios that include precious metals and oil. Furthermore, Crude oil is the one of the most important energy resources in the world and influences the economy and financial markets. In the first essay, we employ smooth transition autoregressive (STAR) model to investigate the nonlinear dynamic behavior of gold price, oil price, and the dollar/euro. The empirical results indicate that these variables exist in a nonlinear relationship. We consider the change rate of the dollar/euro as the threshold value that represents the dynamic LSTAR-type process, whereas the oil price as the threshold value represents the smooth symmetric ESTAR-type process. The results present the greater threshold effect that exists between the gold price and the change rate of the dollar/euro. In the second and third assay, we apply the PSTR model to analysis threshold effect of oil price changes and private consumption expenditures between oil-exporting and oil-importing countries. We use the oil price of one lag period as the threshold variable to explore the nonlinear relationship. The results indicate the value of threshold variable in the low and high regimes will cause consumer to decrease consumption expenditures in oil-exporting countries. When we consider the oil-importing countries, oil price changes will induce the consumption expenditure increase insensitively in the low and high regimes. On the contrary, the oil price changes will reduce the consumption expenditures in the middle regime.
