Collaborative Research: Experimental Evidence on Monetary Policies

2008年至2009年的大衰退促使各国央行尝试非传统货币政策，例如日本、英国和美国的量化宽松政策，以及丹麦、瑞典和欧元区的超额准备金负利率。然而，由于需要在可预见的范围内避免这些非传统政策产生有害的宏观经济影响，政策试验的范围大大受到限制。在这个项目中，我们制定了一个议程，在实验实验室的受控条件下更广泛地进行货币政策实验，目的是在各种货币政策可能在该领域实施之前了解其福利后果。我们的方法类似于飞机被允许飞行前的风洞测试。与实地实验相比，在必要的小规模、低风险的实验室环境中对货币政策进行研究的限制或成本要低得多，因此可以对一套更丰富、甚至更激进的货币政策进行评估。事实上，我们的目标是提供新的证据，证明各种货币政策对福利的影响，这些政策即使不是不可能，至少在没有证据证明其有效性的情况下，也很难在该领域实施。我们寻求开始收集这类证据的过程。我们更大的目标是证明，在评估不同货币政策的有效性时，货币政策的实验室测试可以成为理论和实地数据实证分析的补充工具。我们的货币政策分析框架是拉各斯和赖特的货币搜索理论模型，这是我们之前在实验室中实施的货币经济学中的一个主要模型。在这个项目中，我们建议使用拉各斯-赖特模型来探索著名的弗里德曼规则（弗里德曼1969）的货币政策。众所周知，弗里德曼法则在各种不同的货币模型中都是最优的，包括拉各斯-赖特模型。从本质上讲，弗里德曼表明，福利最大化的货币政策是设定通货膨胀，使名义利率——私人持有货币的边际成本——等于零。由于生产更多货币的社会边际成本基本上为零，如果私人边际成本为正，就会存在一个低效的缺口，而这个缺口可以通过使名义利率等于零来弥补。由此可见，如果安全政府债券的实际收益率为ñ0，而名义利率i，如费雪方程所示为i= EI + ñ，其中EI表示预期通货膨胀率，那么，为了使i=0，央行应该努力使EI = -ñ 0。虽然央行行长们无疑意识到弗里德曼法则，并经常表达对低通胀的真诚愿望，但央行行长们主张（更不用说试图实施）弗里德曼法则通常要求的负通胀率（通货紧缩），这将与传统智慧背道而驰。在实验室中，我们不受这些考虑的约束，因此我们建议以两种不同的方式实施弗里德曼规则，并评估其福利影响。第一种方法是上述类型的通货紧缩货币政策。第二种方法是对货币持有支付具有竞争力的市场利率，完全消除私人持有货币的边际成本。与第一种方法一样，对手头现金持有提供利息的实际性很可能使这种可能性变得不可行。在这个项目中，我们首次在我们的实验性拉各斯-赖特经济中探索弗里德曼规则的两种实现。除了探索弗里德曼规则的两种不同实施的福利后果之外，我们还对使用我们的框架来研究通货膨胀政策的福利后果感兴趣。具体来说，我们对低通胀率与高通胀率的福利成本感兴趣，我们建议通过改变货币增长率来解决这个问题。最后，继我们之前的一项研究之后，我们希望研究对法定货币使用的法律限制（例如纳税）是否对法定货币的采用和福利有影响。

The Great Recession of 2008-09 led central banks to experiment with non-traditional monetary policies, for example, quantitative easing in Japan, the U.K. and the U.S. and negative interest rates on excess reserves in Denmark, Sweden and the Eurozone. Nevertheless, the extent of policy experimentation was greatly tempered by the need to avoid, to the extent foreseeable, harmful macroeconomic impacts from these non-traditional policies. In this project we set out an agenda for conducting monetary policy experiments more broadly in the controlled conditions of the experimental laboratory with the aim of understanding the welfare consequences of various monetary policies prior to their possible implementation in the field. Our approach is analogous to wind-tunnel testing of aircraft before the aircraft is allowed to fly. The study of monetary policies in the necessarily small-scale, low-stakes laboratory environment with paid human subjects is much less restrictive or expensive than experimentation in the field, thereby allowing for evaluation of a much richer and even radical set of monetary policies. Indeed, our aim is to provide new evidence on the welfare impacts of various monetary policies that would be difficult, if not impossible to implement in the field at least without some prior evidence on their effectiveness. We seek to begin the process of gathering such evidence. Our larger goal is to demonstrate that laboratory tests of monetary policies can be a complementary tool to theory and empirical analysis of field data in the evaluation of the efficacy of different monetary policies.Our framework for monetary policy analysis is Lagos and Wright's search-theoretic model of money, a work-horse model in monetary economics that we have previously implemented in the laboratory. In this project we propose to use the Lagos-Wright model to explore the celebrated Friedman rule (Friedman 1969) for monetary policy. The Friedman rule is known to be optimal in a very wide variety of different monetary models, including the Lagos-Wright model. In essence, Friedman showed that the welfare-maximizing monetary policy is to set inflation so as to make the nominal interest rate - the private marginal cost of holding money -- equal to zero. Since the social marginal cost of producing more money is essentially zero, if the private marginal cost were positive, there would be an inefficient gap that could be closed by making the nominal interest rate equal to zero. It follows that, if the real rate of return on safe government bonds is ñ0, and the nominal interest rate, i, as given by the Fisher equation, is i= EI + ñ, where EI denotes the expected inflation rate, then, in order for i=0 the central bank should work to set EI = -ñ 0. While central bankers are undoubtedly aware of the Friedman rule and often express a genuine desire for low inflation, it would be very much against conventional wisdom for central bankers to argue for, let alone attempt to implement, a negative inflation rate (deflation) as the Friedman rule would typically require. In the laboratory we are not bound by such considerations and thus we propose to implement the Friedman rule in two different ways and assess the welfare implications. The first approach is a deflationary monetary policy of the type outlined above. The second approach is to pay a competitive market interest rate on money holdings removing altogether the private marginal cost from holding money. As with the first approach, the practicalities of providing interest on hand-to-hand cash holdings has likely rendered this possibility unworkable. In this project we explore, for the first time both implementations of the Friedman rule in our experimental Lagos-Wright economy. In addition to exploring the welfare consequences of the two different implementations of the Friedman rule, we are also interested in using our framework to study the welfare consequences of inflationary policies. Specifically, we are interested in the welfare costs of low versus high inflation rates, and we propose to address this question by varying the money growth rate. Finally, following up on one of our previous studies, we wish to study whether legal restrictions on the use of fiat money (e.g. to pay taxes) matter for the adoption of fiat money and for welfare.