供求冲击、异质性预期与货币政策范式选择

Shocks of Supply and Demand,Idiosyncratic Expectations and the Choice of Monetary Policy Paradigms

文章构建新凯恩斯模型,研究了供求冲击和异质性预期下,不同货币政策调控范式的有效性。研究发现:中国的经济波动主要由需求冲击所驱动,预期呈现出理性预期和适应性预期混合的异质性特征,货币政策表现出明显的相机抉择倾向;需求冲击导致经济波动向稳态收敛的时间明显长于供给冲击,预期的理性程度提高有助于增进整体福利,事前承诺不一定优于相机抉择,尤其当预期呈现异质性特征时;货币政策忽视利率稳定化操作将导致更多的整体福利损失,需求冲击下这一损失又显著大于供给冲击下。文章认为:在当前预期呈现异质性特征的背景下,相机抉择型调控具有合理性,货币政策不宜盲目向事前承诺转型;在经济波动主要由需求冲击所驱动时,货币政策应考虑利率稳定化因素,保持稳健中性基调可防止不必要的利率扰动影响金融稳定,从而减少福利损失;长期来看,改善公众预期,逐步摆脱外需依赖,大力推进供给侧结构性改革,有助于提升货币政策调控的经济稳定作用。

Since the 2008 international financial crisis,many countries have returned to the discretionary paradigm in macroeconomic regulation.China’s 2017 Government Work Report also stressed to strengthen discretionary regulation of monetary policies for the first time.But up to now,scholars have not reached a consensus about which one is better between discretionary and ex-ante commitment paradigms.Most of the researches support the viewpoint that playing by the rule can improve the credibility of monetary policies with containing ex-ante commitment mechanism.However,the flexibility and pertinence of discretionary regulation undoubtedly play an important role in making the economy out of recession.So this paper aims to quantitatively analyze the economic stabilization effects of discretionary and ex-ante commitment paradigms by a new Keynesian model.Most of the literature uses the new Keynesian framework to make an analysis based on the rational expectation hypothesis.But in China,people have obviously idiosyncratic expectations and the rational degree of expectations needs to improve.So the monetary policy analysis based on the rational expectation hypothesis is not applicable to current reality.The 2016 Central Economic Working Conference firstly put forward'maintaining prudential and neutral monetary policies',but most of the monetary policy literature omits the impact of interest rate adjustment,so that the conclusions couldn’t adapt to the value orientation of current monetary policies.To accurately understand the efficiency of discretionary paradigms in the current Chinese context,this paper builds a new Keynesian model including idiosyncratic expectations and induces the formulas for discretionary and ex-ante commitment paradigms based on the triple-target loss welfare function with interest rate stabilization by the central bank.It shows that:(1)The demand shock mainly derives Chinese economic fluctuations,idiosyncratic expectations consist of rational ingredient and adaptive ingredient,and monetary policies incline to discretion.(2)The demand shock leads to a more sluggish economic fluctuation convergence than the supply shock,improving the rational degree of expectations helps to promote the whole welfare,and ex-ante commitment is not necessarily better than discretion,specifically when idiosyncratic expectations exists.(3)Monetary policies without interest rate stabilization operation result in a greater welfare loss,and the loss is greater under the demand shock than under the supply shock.It suggests that:(1)Discretion is reasonable under idiosyncratic expectations,and monetary policies shouldn’t be blindly transformed into the ex-ante commitment paradigm.(2)Monetary policies must be focused on interest rate stabilization under the condition of economic fluctuations mainly driven by the demand shock,and prudential and neutral monetary policies can prevent unnecessary interest disturbance from affecting financial stability,so as to promote large reduction in the welfare loss.(3)In the long run,improving public expectations,gradually getting rid of external dependence and vigorously pushing the supply-side structural reform can improve the stabilization effects of monetary policy regulation.