二、貨幣流通速度變動率的實證結果則不符合本文預期，與核心物價年增率的相關係數為負，推測可能原因為央行貨幣政策的干預與金融海嘯後，美國民眾儲蓄率的上升與銀行信貸轉趨保守有關。 Abstract: Since2009, Federal Reserve System (Fed) had financed over $1.2 trillion for the U.S. government but the annual budget deficit of government was still over $1 trillion from 2009 to 2012. Massive quantitative easing (QE) and buying government bonds caused the balance sheet of Fed which had amplified from $920 billion in March 2008 to over $3 trillion in the end of 2012. Although the huge amount of money and the serious government budget deficit existed at the same time there was no inflationary pressure in the United States. We used the federal funds rate, velocity of money, and the public debt ratio of GDP over the past 12 years to try to explain the current phenomenon of inflation in the United States. Most of previous studies used time series method, such like Granger Causality, impulse response functions. We applied Copula functions to find the best dependence of inflation and macroeconomic variables through the optimization of Copula functions and try to explain economic implications. The empirical results as following:
1.The empirical result of federal funds rate and public debt ratio of GDP consist with our expectation. The correlation coefficient between inflation and the former is positive and the latter is negative.
2.The correlation coefficient between inflation and velocity of money is negative which is different from our expectation. Our inferences are the intervention of monetary policy of central bank, the rise of saving rate, and the prudence of bank lending after the financial crisis in 2008.