非关税措施量化公式评价

与直接可以用税率高低来度量其保护程度的关税不一样．非关税措施是一种隐蔽的难以直接度量其保护作用的贸易保护主义手段。本文评价了近年来国外普遍采用的非关税措施保护作用的量化方法,包括频度——类型测算法、价格对比测算法、支持率测算法的设计思路和运用状况．以便为不时发生的贸易争端和贸易谈判提供可以用来判断进口国非关税措施保护程度的分析工具。     

Numerical solutions to an integro-differential parabolic problem arising in the pricing of financial options in a Levy market

We study the numerical solutions for an integro-differential parabolic problem modeling a process with jumps and stochastic volatility in financial mathematics. We present two general algorithms to calculate numerical solutions. The algorithms are implemented in PDE2D, a general-purpose, partial differential equation solver.     

Heterogeneity and assessment uncertainties in forest characteristics and biomass carbon stocks: Important considerations for climate mitigation policies

The management of forests to store carbon and mitigate climate change has received significant international attention during the last decade. Using in situ data from a 2008–2009 forest inventory field campaign in Sri Lanka, this study describes the structural characteristics and carbon stocks of six natural forest types. This paper has a dual scope: i) to highlight the variation in carbon stored in aboveground biomass within and between forest types and ii) to determine the implications of the allometric equations chosen to calculate biomass carbon stocks. This study concerns work related to climate change interventions, such as Reducing Emissions from Deforestation and Forest Degradation (REDD+) and other forest-related, performance-based initiatives that require proper monitoring, reporting, and verification of carbon stocks, sinks and emissions. The results revealed that forests are heterogeneous in terms of tree density and height–diameter relationships, both between and within the six forest types investigated. The mean aboveground carbon stock in the different forest types ranged from 22 to 181 Mg C ha⁻¹, and there were statistically significant differences in the carbon stocks of the six forest types in 7 of 15 cases. The estimated carbon stock depended heavily on the allometric equation used for the calculations, the variables, and its application to the specific life zone. Due to the diversity of forest structures, these results suggest that caution should be taken when applying default values to estimate forest carbon stocks and emission values in reporting and accounting schemes. The results also indicated the need for allometric equations that are context-specific for different forest types. Therefore, new field investigations and measurements are needed to determine these specific allometric equations, as well as the potential variation in forest carbon stocks in tropical natural forests.     

Local determinacy of prices in an overlapping generations model with continuous trading

We characterize the determinacy properties of the intertemporal equilibrium for a continuous-time, pure-exchange, overlapping generations economy with logarithmic preferences. Using recent advances in the theory of functional differential equations, we show that the equilibrium is locally unique and that prices converge to a balanced growth path and are determined.     

Measuring Structural Unemployment: NAWRU Estimates in the Nordic Countries

The non-accelerating wage rate of unemployment (NAWRU indicator), used by the OECD as a measure of structural unemployment, has risen for the four Nordic countries Denmark, Finland, Norway and Sweden. In this paper we present stable empirical wage equations for the same countries over the period 1964–1994, in sharp contrast to the increased NAWRU estimates. The instability of the NAWRU estimates is an artefact of a misspecified underlying wage equation, and not due to instability in wage setting itself.
JEL classification : E 24; E 31; E 64; J 51     

Optimal Consumption-Portfolio Policies With Habit Formation1

This is a companion paper to the authors ‘Asset Prices in an Exchange Economy with Habit Formation” in Econometrica which focuses on consumption demand and asset pricing when preferences are habit forming. Here we prove existence of optimal consumption-portfolio policies for (i) utility functions for which the marginal cost of consumption (MCC) interacts with the habit formation process and satisfies a recursive integral equation with forward functional Lipschitz integrand and (ii) utilities for which the MCC is independent of the standard of living and satisfies a recursive integral equation with locally Lipschitz integrand. Result (i) is demonstrated here for the first time. Result (ii) is novel and enables us to consider Cobb-Douglas utilities without placing lower bounds on the system of Arrow-Debreu prices. We also review and extend our earlier results in the linear case; in particular, we provide new insights about the structure of optimal portfolios. Additional new features of the model include the possibility of finite marginal utility of consumption at zero and habit formation mechanisms with stochastic coefficients. an extension to a financial market model with general processes is outlined. A byproduct of the analysis is a set of fixed-point theorems for recursive integral equations with forward functional Lipschitz or locally Lipschitz integrands.     

Is There Excess Capacity in Rural Banking Markets?

The literature indicates that it is difficult to identify and quantify the degree of excess capacity in banking. Economic theory indicates that there are at least three indicators of excess capacity in banking: (a) low loan-to-asset ratios, (b) low profitability and (c) high per unit operating expense relative to some norm. If excess capacity exists, it will be easiest to identify, through these indicators, at small rural banks. This paper finds significant evidence of excess capacity at rural Colorado banks using univariate analysis; simultaneous equations analysis reinforces this conclusion. It appears that the “excess capacity effect”outweighs the “market power effect”in these rural banking markets.     

Trade responses to geographic frictions: A decomposition using micro-data

A large literature has shown that geographic frictions reduce trade, but has not clarified precisely why. In this paper, we provide some insight into why such frictions matter by examining what parts of trade these frictions reduce most. Using data that track manufacturers’ shipments within the US on an exceptionally fine grid, we find that the pattern of shipments is extremely localized. Shipments within 5-digit zip codes, which have a median radius of just 4 miles, are 3 times larger than shipments outside the zip code. We decompose aggregate shipments into extensive and intensive margins, and show that distance and other frictions reduce aggregate trade values primarily by reducing the number of commodities shipped and the number of establishments shipping. Extensive margins are particularly important over very short distances. We examine trade in intermediate goods as an explanation for highly localized shipments and the dominant role of the extensive margin and find evidence consistent with this hypothesis. In another significant finding, we find no evidence of state-level home bias when distances are measured precisely and trade is observed over a very fine grid.     

Relative arbitrage in volatility-stabilized markets

Summary. We provide simple, easy-to-test criteria for the existence of relative arbitrage in equity markets. These criteria postulate essentially that the excess growth rate of the market portfolio, a positive quantity that can be estimated or even computed from a given market structure, be sufficiently large. We show that conditions which satisfy these criteria are manifestly present in the U.S. equity market. We then construct examples of abstract markets in which the criteria hold. These abstract markets allow us to isolate conditions similar to those prevalent in actual markets, and to construct explicit portfolios under these conditions. We study in some detail a specific example of an abstract market which is volatility-stabilized, in that the return from the market portfolio has constant drift and variance rates while the smallest stocks are assigned the largest volatilities. A rather interesting probabilistic structure emerges, in which time changes and the asymptotic theory for planar Brownian motion play crucial roles. The largest stock and the overall market grow at the same, constant rate, though individual stocks fluctuate widely.We are indebted to Adrian Banner and Constantinos Kardaras for several helpful discussions; in particular, the computation of (4.27) is due to Adrian Banner. We are also grateful to Professors Chris Rogers and Marc Yor for their expert advice on the subject of planar Brownian motion, and to Professor Peter Bank for an observation that helped us correct an error in an earlier version of the paper.This revised version was published online in January 2005 with corrections to the Cover date.     

A linear demand system within a seemingly unrelated time series equations framework

A seemingly unrelated time series equations framework for the linear almost ideal (AID) demand system is considered. The framework is applied to a consumer demand system covering nine non-durable commodities. Within a specification where the static linear AID system is augmented by latent variables representing stochastic trends and seasonality, demand homogeneity is tested; both in each equation and in the system as a whole. Income and own-price elasticities are calculated under homogeneity restrictions. Although the homogeneous model is formally rejected by statistical tests, it performs well with respect to interpretability, parameter stability and forecasting.