在第二章中，我们主要介绍了潜在产出估计的研究现状。在实证研究领域，主要有五种方法用于估计潜在产出：第一种方法是分离趋势法，例如HP滤波，以及Baxter和King(1991)提出的BK滤波；第二种方法是增长率推算法；第三种方法是生产函数法，这也是实证研究领域最常用的一种方法，美国、日本和韩国所公布的官方潜在产出估计都是采用了这种方法；第四种方法是利用基于菲利普斯曲线和奥肯定律的状态空间模型(Apel and Jansson,1999)；第五种方法是数据包络分析（Data Envelopment Analysis）方法。在简要分析我国部分学者利用生产函数法研究潜在产出的不足后，本文将应用其中的分离趋势法和生产函数法对我国的潜在产出和产出缺口进行估算。
在文章的第三章中，我们给出分离趋势法和生产函数法的估计思路，并详细的论述了两种方法所涉及到的主要理论模型：HP滤波、Cobb-Douglas生产函数和索洛增长模型。利用上述两种方法并结合我国的实际数据得到潜在产出及产出缺口的估计。需要强调的是本文采用与通常生产函数法研究潜在产出所不同的估计思想：将真实投资、折旧率与实际GDP增长率（指数增长）代入索洛均衡增长模型，得到在现有投资和GDP增长率的前提下，所利用到的资本存量的估计值 ；考虑两要素、技术外生、规模报酬不变的Cobb-Douglas生产函数模型，将实际GDP、资本存量 和实际就业人口代入取对数线形化后的模型，得到模型的参数估计，将资本存量总量和经济活动人口作为潜在经济运行水平下的要素投入，代入已知参数估计的模型中，得到潜在产出。
About much positive research, countries all over the world of economic growth is it involve to potential estimation of output to want correctly, in economical operation, real GDP always fluctuates with the circulation in economic cycle up and down in potential GDP level, estimate out the potential output of economy of a regular period, for analysing the economic situation of this period, clarify the origins of the economic fluctuation and economic tendency of prediction will be all significant. Because potential GDP is the economic variable that the statistical department can't observe, a lot of national government departments all carry on the ration to estimate to potential GDP.
Among this page article, we strain with HP filter , Cobb-Douglas production function and Solow increase model build the model of standing for theoretical foundation, estimate that receives the level of potential output of our country. On this basis, we analyse , compare with the relation of fluctuating in economic cycle to the gap of the output, is it resolve to go on to potential output rate of increase , analyse every change of key element to potential output contribution of rate of increase, thus verified the gap of outputs has an important guidance function to the marcoeconomic regulation and control of our country.
In chapter one of this text, we have introduced economic growth, economic cycle and potential output mainly, point out the relation between the three. Medium and long-term, estimate the potential output and output gap, contribute to policymaker's confirming the space of the sustainable real economic growth, make and appraise the foundation of the macro economic policy. To the comparison of the level of the realistic output and potential output level, can confirm as and guarantee economy is steady, grow at top speed, the economic policy is to rely mainly on increasing the aggregate demand for the main fact by adjusting economic structure. Output gap can recognise economy live in economic cycle position of circulation, determine the output periodicity and deviate from the potential output or the quantity of the trend output value, its tolerance actual output and economy existing resource fully difference of output can produced to utilize.
In chapter two, research current situation that we have introduced the potential output and estimated mainly. In the field of positive research, five kinds of methods are used in the potential output of estimation mainly: The first kind of method is to separate the trend method, for example HP filter, and BK filter that Baxter and King (1991 ) put forward; The second kind of method is that the rate of increase calculates method; The third kind of method is a production function approach, this is a kind of most frequently used methods of research field of real example too, U.S.A., Japan, S. Korea potential output of official side that announce estimate that has adopted this kind of method; The fourth kind of method is to utilize the model (Apel and Jansson of state space based on Philips' curve and Okun’s law ,1999); The fifth kind of method is Data Envelopment Analysis. After analysing briefly some scholars of our country utilize the production function approach to study the deficiency of the potential output, this text will use separation trend law and production function approach among them to estimate to potential output and output gap of our country.
In chapter three of the article, we provide and separate the trend method and thinking of estimation of the production function approach, and the main theory model that two kinds of methods of detailed argumentation involve: HP filter, Cobb-Douglas production function and Solow and increases models. Utilize above-mentioned two kinds of methods and real data combining our country to get the estimations of the potential output and output gap. Whether need emphasize copies of literary grace spend with production function approach study potential output different estimation thought usually. Is it enter true investment, rate of depreciation, actual GDP rate of increase (index increase ) Solow increase models proportionally to take the place of, get it on the premise of existing investment and GDP rate of increase, the estimated value of the stock of the capital utilized; Consider two key element, catch, Cobb-Douglas production function model that returns to scale do not outside the technology, is it is it fetch logarithm line model after the shape to enter to take the place of actual GDP, capital stock and actual employed population, the parameter of receiving model estimates, regard total amount of the stock of the capital and economic activity population as the factor input under the potential economical operation level, take the place of enter known model that parameter estimates, get the potential output.
In chapter four, we use the estimation result of the first chapter, further investigate output gap and relevant compositions related to and potential output rate of increase in economic cycle of our country. Compare calculating the output gap got with the reality economic cycle of our country and change on economic structure, find the fluctuation in economic cycle of the fluctuation of the gap of outputs and our country is very identical, the result that the production function approach gets embodies our country and utilizes the change of degree from planned economy to the factor of production in transition period of market economy especially. Output got gap can fine explanation economic structure change and different bias of actual output and potential output that economic policy lead to the fact very, for realize economy to be steady growing at top speed macro adjustment and control policy adopted to need offer the basis.
Finally, the gap and result that is compared and analysed of relevant economic indicator happen domestically to me according to the above, we find: Of our country periodic operation of economy to cause in different different macro economic policy of content that period issue by government to a great extent, in other words, namely caused by government's discontinuous macro economic policy. So, in order to keep economic stability, high-speed growth, the government's macro adjustments and controls function is particularly important. Whether combine of our country economy actual running situation, propose one suggestion, period of macro adjustment and control policy in the future. First, from invest in and consume two heavy domestic structure of demand these not to is it watch to come, adjust and control some overheated investment demand those, expand the consumption demand; Second, from invest in inside structure watch, adjust and control some overheated trade, high consumption high pollute and image project, top-grade house of all parts, afford to enclose, expand it to agriculture, the tertiary industry that can absorb employment and investment of different social cause; Third, from consume inside structure watch, control extravagant and wasteful, corruption, banquet at public expense and consumption that public money travel etc., expand the income and consumption of peasants , urban middle and low income group; Fourth, by the look of regional structure, should consider the disequilibrium of regional development, adjust and control some and overheated place, expand it to west and investment of such old industrial bases as the Northeast ,etc..
The estimation result of receiving model is not a final purpose, the each important one provides the corresponding policy recommendations according to the estimation of the model. We think, through the structural appropriate fine setting, expand macro adjustments and controls that is accused of, can make economic growth rate of the following several years steady among 8-9%.