Pay-as-you-go social security in a changing environment

In this paper, we examine the optimal pay-as-you-go social security scheme which reallocates resources across generations in a changing environment, that is, with fluctuations in population growth rates and in productivity levels. We use an overlapping generations model along with a social welfare function consisting of the sum of generational utilities either unweighted or weighted by population size and a discount factor. We show how intergenerational resource sharing can be used to improve social welfare even though the extent of intergenerational redistribution is hampered by payroll tax deadweight losses in the spirit of the optimal taxation literature. Also it appears that resource sharing is much more restricted in a closed economy that in an open economy, which is not subject to a national resource constraint at each period of time. This paper was presented at the 1990 ISPE-Conference on the Fiscal Implications of an Ageing Population, Vaalsbroek Castle, Netherlands. The authors wish to thank the participants and particularly B. van Praag and W. Peters for their comments. They also thank the two referees and Philippe Michel for very helpful comments and discussions. The financial support of CIM during his sabbatical year is greatly acknowledged by the second author.     

Insider Trading,Stochastic Liquidity,and Equilibrium Prices

We extend Kyle's (1985) model of insider trading to the case where noise trading volatility follows a general stochastic process. We determine conditions under which, in equilibrium, price impact and price volatility are both stochastic, driven by shocks to uninformed volume even though the fundamental value is constant. The volatility of price volatility appears ‘excessive’ because insiders choose to trade more aggressively (and thus more information is revealed) when uninformed volume is higher and price impact is lower. This generates a positive relation between price volatility and trading volume, giving rise to an endogenous subordinate stochastic process for prices.     

QUOTA‐HOPPING IN‐BOND DIVERSION

We show that the U.S. in‐bond system of imports may be used by firms to illegally avoid trade barriers, a practice known as in‐bond diversion. The illicit scheme involves declaring Chinese exports bound for Mexico but diverting them to the U.S. market while in transit, thus creating a gap between Chinese and Mexican reports. Using the phaseout and removal of U.S. quotas at the end of the Multifiber Agreement as a policy experiment, as well as variation in quota bindingness across products, we show that quota‐bound products were associated with larger trade gaps which shrunk following the quota removals. (JEL F13, O17, O19)     

Multivariate hypothesis testing using generalized and {2}-inverses – with applications

The use of generalized inverses in Wald's-type quadratic forms of test statistics having singular normal limiting distributions does not guarantee to obtain chi-square limiting distributions. In this article, the use of {2} -inverses for that problem is investigated. Alternatively, Imhof-based test statistics can also be defined, which converge in distribution to weighted sum of chi-square variables. The asymptotic distributions of these test statistics under the null and alternative hypotheses are discussed. Under fixed and local alternatives, the asymptotic powers are compared theoretically. Simulation studies are also performed to compare the exact powers of the test statistics in finite samples. A data analysis on the temperature and precipitation variability in the European Alps illustrates the proposed methods.     

Si-GARCH: Construction and validation of a new method for the detection of breaking points in models

In this article, we define a new method (Si-GARCH) for signal segmentation based on a class of models coming from econometrics. We make use of these models not to perform prediction but to characterize portions of signals. This enables us to compare these portions in order to determine if there is a change in the signal’s dynamics and to define breaking points with an aim of segmenting it according to its dynamics. We, then, expand these models by defining a new coefficient to improve their accuracy. The Si-GARCH method was tested on several thousands of hours of biomedical signals coming from intensive care units.     

BIDDING FOR HORIZONTAL MULTINATIONALS

We present a model in which governments bid for firms by taxing/subsidizing setup costs. Firms choose both the number and the location of the plants they operate, and the equilibrium industry structure is affected by governments' subsidy choices. We show that the endogenous presence of horizontal multinationals attenuates the race to the bottom and yields some results that run counter to traditional findings in the literature. First, in the presence of multinationals, increasing subsidies decrease firms' profits by exacerbating price competition due to more firms going multinational. Second, instead of being always subsidized, firms may actually be taxed in equilibrium. Last, subsidies may become strategically independent policy instruments, instead of being strategic complements. (JEL: F12, F23, H27, H73, R12)     

RELATIVE RISK AVERSION IS CONSTANT: EVIDENCE FROM PANEL DATA

Most classical tests of constant relative risk aversion (CRRA) based on individual portfolio composition use cross‐sectional data. Such tests must assume that the distributions of wealth and preferences are independent. We use panel data to analyze how individuals’ portfolio allocation between risky and riskless assets varies in response to changes in total financial wealth. We find the elasticity of the risky asset share to wealth to be small and statistically insignificant, supporting the CRRA assumption; this finding is robust when the sample is restricted to households experiencing large income variations. In addition, we find a small but significant negative correlation between wealth and risk aversion. Various extensions are discussed.     

DO PRICES TRANSMIT RATIONALLY EXPECTED INFORMATION?

A simple model with asymmetric information, in which inventory holders or traders submit demand curves to an auctioneer, has a unique partially revealing equilibrium. We wonder whether the agents can plausibly coordinate on this equilibrium through “eductive” reasoning relying on common knowledge. The analysis stresses the role of two effects, sensitivity and amplification, whose product should be small enough. The property is obtained whenever the equilibrium excess demand is steep enough, i.e., when the search for information does not distort demand too much. Neither the influence of the number of informed agents nor that of noise trading are monotonic. Real‐time learning has strikingly different features. (JEL: D82, D84)     

The Dynamics of Inequality

The past forty years have seen a rapid rise in top income inequality in the United States. While there is a large number of existing theories of the Pareto tail of the long‐run income distributions, almost none of these address the fast rise in top inequality observed in the data. We show that standard theories, which build on a random growth mechanism, generate transition dynamics that are too slow relative to those observed in the data. We then suggest two parsimonious deviations from the canonical model that can explain such changes: “scale dependence” that may arise from changes in skill prices, and “type dependence,” that is, the presence of some “high‐growth types.” These deviations are consistent with theories in which the increase in top income inequality is driven by the rise of “superstar” entrepreneurs or managers.