i. Currency mismatch and economic growth: Razin and Collins (1997) indicate that the exchange rate mismatch, i.e. the exchange rate deviation from PPP, occurs in both developing and developed countries but only the serious overestimation affects economic growth. Generally, exchange rates are moderately underestimated in countries with rapid economic growth. Thus, PPP test is an extremely important tool to monitor policy makers and ensure economic growth. In the late 1990s, the Asian financial crisis caused great damage to the Asian countries and even the world’s economy. Meanwhile, people have the chance to see the critical negative outcome of exchange rate overvaluation and inappropriate exchange rate regime and monetary policy errors. During the Asian financial crisis, China also suffered a shock. To stabilize the world’s economy, China has promised not to devalue the RMB, that actually caused the overestimation of Yuan, and that in turn caused the damage directly on Chinese import and export trade that year. And after year 2003, the appreciation of Chinese Yuan is also facing strong pressure. But whether the Yuan is undervalued or overvalued in the end is a highly debated factor. Therefore, the empirical study of purchasing power parity of RMB has very practical significances, mainly in determining the nominal exchange rate anchor or whether there is a serious mismatch, maintaining sustained and stable growth of China’s economy, and providing protections for the improvement of China’s exchange rate system.
Thus, regardless of other developing countries, or China itself, the empirical test of purchasing power parity theory has great significances: it is not only a country’s policy maker in deciding the choice of exchange rate regime and a powerful tool to determine the form of monetary union, but also provides a standard to compare levels of development between countries. Test purchasing power parity is also important for forecasting the financial crisis and providing a reliable guide. In short, the purchasing power parity tests play an important role in different areas of the economy. It is certain that, as the economic and financial environment changes, the continuous inspection for purchasing power parity is necessary, and in the future it will not stop.
一、货币错配与经济增长：拉辛和柯林斯（1997）表明，汇率的不匹配，即从购买力平价汇率偏差，发生在发展中国家和发达国家，但只有严重高估对经济增长的影响。一般来说，汇率适度经济快速增长国家低估。因此，PPP测试是监测政策制定者和保证经济增长的一个非常重要的工具。在上世纪90年代末，亚洲金融危机的亚洲国家乃至世界经济造成巨大的损失。同时，人们有机会看到汇率高估和不恰当的汇率制度与货币政策的错误批判否定的结果。在亚洲金融危机中，中国也遭受了冲击。对稳定世界经济，中国承诺人民币不贬值，这实际上造成人民币高估，进而造成损害的直接对中国进出口贸易，年。和2003年后，人民币升值也面临着强大的压力。但人民币是否被低估或高估的到底是一个极具争议的因素。因此，对人民币购买力平价的实证研究具有非常现实的意义，主要是确定的名义汇率锚或是否有严重失配，保持中国经济持续稳定的增长，为中国的汇率制度的完善提供保护。
因此，无论是发展中国家，还是中国本身，购买力平价理论的实证检验具有重要的意义：在决定汇率制度的选择和确定货币联盟的形成一个强大的工具，它不仅是一个国家的政策制定者，而且还提供了一个标准来比较各国之间发展水平。测试的购买力平价预测金融危机，提供可靠的指导也很重要。总之，购买力平价试验在不同的经济领域发挥着重要的作用。可以肯定的是，随着经济和金融环境的变化，对购买力平价是必要的连续检测，并在未来将不会停止。
