Diversification discount and investor sentiment

While previous research has linked the diversification discount to suboptimal managerial decisions, recent empirical work and methods have shown these relationships are not as strong. A rational learning framework indicates the diversification discount is related to economic activity. Building on this framework, we test and find support for the hypothesis that investor sentiment explains the diversification discount. Investor sentiment favors riskier firms when sentiment is high, thereby increasing returns and relative valuations. As a result, diversified firms imputed value based on these multiples leads to a larger diversification discount and reverses when sentiment falls.     

RISE OF VAR MODELLING APPROACH*

Abstract This paper surveys the rise of the Vector AutoRegressive (VAR) approach from a historical perspective. It shows that the VAR approach arises from a fusion of the Cowles Commission tradition and time series statistical methods, catalysed by the rational expectations (RE) movement, that the approach offers a systematic solution to the issue of ‘model choice’ bypassed by Cowles researchers, hence essentially inheriting and enhancing the Cowles legacy rather than abandoning or opposing it. By tackling model choice, however, the VAR approach helps reform econometrics by shifting the research focus from measurement of given theories to identification/verification of data‐coherent theories.     

Solving generalized multivariate linear rational expectations models

We generalize the linear rational expectations solution method of Whiteman (1983) to the multivariate case. This facilitates the use of a generic exogenous driving process that must only satisfy covariance stationarity. Multivariate cross-equation restrictions linking the Wold representation of the exogenous process to the endogenous variables of the rational expectations model are obtained. We argue that this approach offers important insights into rational expectations models. We give two examples in the paper—an asset pricing model with incomplete information and a monetary model with observationally equivalent monetary-fiscal policy interactions. We relate our solution methodology to other popular approaches to solving multivariate linear rational expectations models, and provide user-friendly code that executes our approach.     

Cohort and target age effects on subjective survival probabilities: Implications for models of the retirement phase

Subjective survival scaling factors are often estimated from one observation of life expectancy and treated as constant to any target age. Using new survey data on subjective survival probabilities, we estimate a model incorporating cohort- and target age-varying beliefs in scaling factors. Both cohort age and target age matter: respondents are pessimistic about overall life expectancy but optimistic about survival at advanced ages, and older respondents are more optimistic than younger. We propose a new theoretical model incorporating cohort- and target age-varying beliefs and illustrate their effects on the perceived value of annuities and on retirement phase consumption plans.     

基于Rational软件系统的应用与研究

本文结合Rational测试工具的使用,对Rational的测试理念及其优势和成功经验进行阐释。     

Rational asset pricing bubbles and debt constraints

Rational price bubble arises when the price of an asset exceeds the asset’s fundamental value, that is, the present value of future dividend payments. The important result of Santos and Woodford (1997) says that price bubbles cannot exist in equilibrium in the standard dynamic asset pricing model with rational agents facing borrowing constraints as long as assets are in strictly positive supply and the present value of total future resources is finite. This paper explores the possibility of asset price bubbles under endogenous debt constraints induced by limited enforcement of debt repayment. Equilibria with endogenous debt constraints are prone to have infinite present value of total resources. We show that asset price bubbles are likely to exist in such equilibria. Further, we demonstrate that there always exist equilibria with price bubbles on assets in zero supply.     

Consumer Rationality and Consumer Sovereignty

Important social benefits of the market system are predicated on the assumption that consumers can effectively pursue their interest in the marketplace. Cause for concern exists to the extent that high consumption expenditures lead to relatively low levels of personal savings in the U.S. To the extent that they do, in fact, over spend, consumers appear to deviate from economic assumptions of rationality. This paper examines four conceptions of rationality (two variants of rational choice theory, institutionalism, and one derived from economic sociology), with a view to evaluating implications for consumer sovereignty under each. By explicitly accounting for differences among individuals, economic sociology appears to offer more realistic policy solutions.     

门诊抗高血压药物应用分析

目的介绍我院门诊抗高血压药物的使用情况,为临床合理用药提供参考。方法选取我院2013年的处方,从中筛选出含有抗高血压药物的处方,采用世界卫生组织（WHO）推荐的限定日剂量（DDD）等方法进行统计、分析。结果 28 208张门诊处方中使用抗高血压药物的处方有5 005张,占总处方数的17.7%。抗高血压药物在门诊使用较多,钙通道拮抗药（CCB）使用率最高,处方中抗高血压药物多为联合用药。结论我院门诊抗高血压药物使用基本合理,大多为联合用药,但仍需进一步提高。     

Structural stability and model design

The paper introduces the concept of structural stability and proposes that it should be considered a necessary property of scientifically valid models. Formalization of the concept is considered in both linear and non-linear models. A strong preference in favour of the wider use of non-linear models is supported by consideration of the dangers of linearization in dynamic models. The importance of structural stability is demonstrated with reference to dynamic rational expectations models which exhibit the saddle-point property. In such cases convergence to equilibrium is shown to be a structurally unstable property which can be forced by restrictive auxillary assumptions, which are highlighted.     

Floating exchange rates versus a monetary union under rational beliefs: the role of endogenous uncertainty

Using the concept of ex-post optimality, we compare different exchange rate regimes, including floating exchange rates and fixed exchange rates with a Monetary Union in a two country OLG model with stochastic endowments. The emphasis of this comparison is on the welfare consequences of agents having incorrect beliefs. We do not assume that agents can hold any beliefs, but rather that their beliefs are rational that is consistent with the observed empirical behavior of the economy. We study a large set of possible policies, but two of them have our particular interest. The first policy implies devaluations in reaction to a negative shock, while the other implies a fixed exchange rate. These policies have very different consequences. The first will for generic beliefs not result in an ex-post optimal allocation. The other policy is on the other hand always feasible and results in an ex-post optimal allocation. When the two countries form a Monetary Union, the ex-post optimal allocation is also achieved. The meaning of “endogenous uncertainty” as an institutionally induced uncertainty is illustrated. Received: September 1, 2001; revised version: 24 June 2002 RID="*" ID="*" I would like to thank Horace W. Brock, Gianluca Cassese, Paula Orlando, Ho-Mou Wu as well as seminar participants at Copenhagen Business School, ESEM98, Keio University, Kyoto University, Osaka University, SITE (Stanford) and University of Copenhagen for many useful comments on the paper. I am also grateful to Mark J. Garmaise, Takako Fujiwara-Greve, and an anonymous referee for many helpful suggestions for improving the paper. Without the many discussions about Rational Beliefs and related issues I have had with Mordecai Kurz over the years, the research presented here would not have been possible. Financial support from The Carlsberg Foundation, Danish Social Research Council, University of Copenhagen and SITE is gratefully acknowledged.