The PPP theory the basis of long-term equilibrium exchange rate determination has received widespread attention since its inception. Over the years, economists have developed a series of important researches around the concept. Although the holding of the PPP needs strict precondition and few economists believe that it can get perfect realization in the real world, most of them still maintain that the PPP is the basic theory in determining the long-term equilibrium exchange rate. Therefore a large number of empirical researches are conducted in order to test the hypothesis of the PPP. Along with the development of quantitative research technique, tests of hypothesis of the PPP, from the early OLS estimation to unit root test and cointegration test, then to the using of long-term data and panel data, are empirical studies which promote the development of the PPP theory. Rogoff (1996) proposed the purchasing power parity puzzle which has made the theory of the PPP enter a new stage. The PPP puzzle is this: How can one reconcile the enormous short-term volatility of real ex-change rates with the extremely slow rate at which shocks appear to damp out? Most interpretations of short-term exchange rate volatility indicate to financial factors like changes in portfolio preferences, short-term asset price bubbles, and monetary shocks. The real economy in the presence of sticky nominal wages and prices can be substantially affected by such shocks.
The PPP theory as the foundation theory of exchange rate has always been one of the most debated topics among economists. As the basic precondition of the Mundell Fleming Model and the New Open Economy theory, the empirical PPP tests provide important theoretical foundations for the decision and police-making of exchange rate. The estimates of the PPP also have significant value in practical applications such as determining the exchange rate parity, coordinating the nominal exchange rate and exchange rate policy, designing the formation mechanism of exchange rate etc. For a country itself, the empirical tests of PPP are not only powerful tools when the government determines exchange rate policy and the form of monetary union but they also provide criterions of comparing development degrees between countries. More importantly, they provide reliable guidelines in the area of forecasting financial crisis.
购买力平价理论的长期均衡汇率决定自成立以来受到广泛关注的基础上。多年来，经济学家们已经开发了一系列重要的研究概念。虽然控股的PPP需要严格的前提条件和一些经济学家相信，它可以在现实世界中得到完美的实现，他们中的大多数人仍然认为PPP是决定长期均衡汇率的基本理论。因此，大量实证研究进行了测试的PPP假说。随着研究技术的发展，购买力平价的假设检验，从早期的OLS估计单位根检验、协整检验，然后长期数据和面板数据的实证研究使用，是促进PPP理论的发展。罗戈夫（1996）提出的购买力平价难题使购买力平价理论进入新阶段。PPP难题是：如何调和，冲击出现潮湿了极其缓慢的速度实际汇率的短期波动？短期汇率波动的解释表明，在投资组合中最喜欢的偏好的变化，金融因素，短期资产价格泡沫，冲击和货币冲击。在名义工资和价格粘性的存在实体经济可以通过这种冲击的实质上的影响。
购买力平价理论，汇率的基础理论一直是经济学家们最为关注的话题。作为蒙代尔-弗莱明模型的基本前提和新开放经济理论，实证PPP测试提供重要的理论基础和警方决定汇率制。的PPP估计在实际应用中，如确定汇率平价也有重要价值，协调的名义汇率和汇率政策，对于一个国家的汇率形成机制的设计等，购买力平价的实证检验，不仅是功能强大的工具，当政府决定汇率政策与货币联盟但他们也提供形式比较国家发展程度的标准。更重要的是，它们提供可靠的指引，预测金融危机的地区。
