Adaptive learning,endogenous uncertainty,and asymmetric dynamics

I present a simple model where forecasting confidence affects aggregate demand. It is shown that this model has similar stability properties, under statistical and evolutionary learning, as a model without a confidence affect. From this setup, I introduce “Expectational Business Cycles” where output fluctuates due to learning, heterogeneous forecasting models and random changes in the efficient forecasting model. Agents use one of two forecasting models to forecast future variables while heterogeneity is dictated via an evolutionary process. Increased uncertainty, due to a shock to the structure of the economy, may result in a sudden decrease in output. As agents learn the equilibrium, output slowly increases to its equilibrium value. Expectational business cycles tend to arrive faster, last longer and are more severe as agents possess less information.     

On the behavior of commodity prices when speculative storage is bounded

This paper investigates the implications of bounded speculative storage, storage bounded from below at zero and above at a capacity, on commodity prices. Binding capacity mirrors the non-negativity constraint on storage and leads to negative price spiking and higher volatility when the market is in deep contango, i.e. low current prices at high stock levels. With bounded storage there is no need to restrict storage to be costly to ensure a rational expectations equilibrium. This allows the model to cover a wide range of storage technologies, including free and productive storage. We also provide an alternative expression for speculative prices that highlights the key role of the storage boundaries. The competitive equilibrium price is the sum of discounted future probability weighted boundary prices. The boundary prices can be viewed as dividends on commodities in storage reflecting the realization of economic profits from storage.     

Switching bubbles: From Outside to Inside Bubbles

The United States has recently experienced two asset price bubbles: the Dot-Com and the Housing Bubbles. These bubbles had very different effects on investment and debt of manufacturing firms. In this paper I develop a framework to understand the differential effect of two types of rational bubbles. I distinguish between (i) Outside Bubbles, which I define as savers purchasing and selling costless assets not-attached to inputs of production and (ii) Inside Bubbles, which I define as savers buying an input of production (e.g., land or houses) only as a store of value. The model is an OLG economy with savers and entrepreneurs. Savers save to consume when they are old. Entrepreneurs can borrow to invest but they face a collateral constraint. In this environment, rational bubbles can emerge. I show that the size of an Inside Bubble is larger. I also find that when the economy switches from an Outside to an Inside Bubble, manufacturing (or non-housing) investment and debt is lower, consistent with the U.S. experience. Finally, I show that even though steady-state consumption is higher with an Outside Bubble, a social planner would prefer an Inside Bubble when the productivity of entrepreneurs is low.     

Mitigation of the Lucas critique with stochastic control methods

Lucas (In: Brunner, K., Meltzer, A.H. (Eds.), The Phillips Curve and the Labor Markets, Supplementary Series to the Journal of Monetary Economics, 1976, pp. 19–46) pointed out, that when optimization is performed on a deterministic macro model, the resulting policy may not reflect the true optimal solution. Private agents may react to announced policies and consequently model parameters will start to drift. The aim of this paper is to develop a methodology for deriving an optimal policy in the presence of rational expectations and parameter drift. This drift is captured by a stochastic optimization framework with time-varying parameters. The resulting optimal policy is capable of tracking changes in the parameters due to policy changes. A numerical example illustrates how the methodology provides a way to mitigate the effects of the Lucas critique.     

有效承接发达地区产业转移的金融政策选择——以广西为例

生产要素流动是区际产业转移的推动器,而此其中资金的流动和投资又是实现产业转移目标和提升产业转移绩效的关键。国内外的成功经验也表明,金融产业转移既是产业转移的重要领域,而且往往又是其中的先行领域,因此现阶段在承接区际产业转移的过程中,大力发展金融产业、积极构建有效的地方系统性的金融政策体系以及制定和实施有效的金融倾斜政策,无疑具有重要的现实意义。     

论住房抵押贷款终止偿付型理性违约

住房抵押贷款债务人不仅会进行提前偿付型理性违约 ,在相关机制不健全时也会进行终止偿付型理性违约。终止偿付型理性违约是指在住房抵押贷款存续期内 ,债务人在自身财务状况正常的情况下 ,因经济理性而从某一时刻起终止继续履行对尚欠贷款本息的偿还责任的违约行为。它发生的客观性在于住房抵押贷款债务人对所购住房损失最小化或收益最大化的财务预期能否顺利实现。建立终止偿付型理性违约发生的条件模型 ,可找出抵押率、贷期、已还款量和已履约时间等变量与条件模型的内在关系 ,进而设计出我国金融机构主动防范终止偿付型理性违约风险的思路。     

中国股市理性预期的检验

理性预期假设在经济金融研究中占据着十分重要的地位 ,但它是否真的与人们的决策行为相一致 ,仍然是并不十分清楚的问题。本文利用中国股市的调查数据 ,对机构的短期预期行为进行了直接的检验。由于数据的分类性质 ,我们发展了解释变量包含离散数据的模型的估计方法。研究中我们没有找到支持理性预期假说的证据。文章对分类调查数据的检验给出了创新性的方法 ,文章的结论有助于人们对中国股民投资和预期行为的认识。     

公榔村土地资源利用现状及其合理开发利用研究

本文在深入分析公榔村土地资源利用现状基础上,针对该村土地利用中存在的问题,提出了合理利用土地的基本原则,并运用线性规划方法对其合理利用结构进行了初步探讨。     

A test for rational bubbles in stock prices

This paper presents two necessary conditions for the absence of rational bubbles on the assumption that the discount rate is stationary. One condition is that real stock prices and real dividends are cointegrated with the time-varying cointegrating vector. The other is that the order of integration of real stock prices is equal to that of real dividends. The first condition is different from that proposed on the assumption of a constant discount rate. In contrast, the second condition is the same as that presented on this assumption. Examining the second condition using Japanese data, we find that Japanese stock prices and dividends satisfy the necessary condition. First version received: May 2000/Final version accepted: April 2001     

Endogenous uncertainty and the non-neutrality of money

Summary. We study some implications of the Theory of Rational Beliefs to monetary policy. We show that monetary policy in a Rational Beliefs environment can have an important effect on the characteristics of economic fluctuations. In Rational Beliefs Equilibria money is generically non-neutral unlike Rational Expectations Equilibria in which money is neutral and monetary policy is ineffective. Under Rational Beliefs Equilibria nominal prices and real output change not only in response to changes in the exogenous growth rate of money but also in response to changes in the state of beliefs. In Rational Beliefs Equilibria monetary shocks have real effects even when they are observed but are not fully anticipated. Furthermore, the non-neutrality of money results in a short run Phillips curve. When money “flutters, real output sputters” [8]. We show that Endogenous Uncertainty and the distribution of market beliefs are the major explanatory variables of such fluctuations. Under Rational Expectations monetary policy is ineffective because agents neutralize it by predicting correctly the effect of the policy. Under Rational Beliefs it is shown instead that inflation and recessions can be substantially aggravated by the distribution of market beliefs. Received: January 14, 2002; revised version: April 5, 2002 RID="*" ID="*" I would like to thank Mordecai Kurz for his constant help and support. Most of the ideas developed hereby have been inspired by innumerable and fruitful discussions with him. I have also greatly benefited from helpful comments by Stanley Black, Luigi Campiglio, Carsten Nielsen and Ho-Mou Wu. I also received valuable remarks from participants at the V meeting of “The Society for the Advancement of Economic Theory” held in Ischia, Italy, on July 2-8, 2001, where an initial draft of the present work was presented.