Regional, national, and spatially explicit scenarios of demographic and economic change based on SRES

We report here spatially explicit scenario interpretations for population and economic activity (GDP) for the time period 1990 to 2100 based on three scenarios (A2, B1, and B2) from the IPCC Special Report on Emissions Scenarios (SRES). At the highest degree of spatial detail, the scenario indicators are calculated at a 0.5 by 0.5 degree resolution. All three scenarios follow the qualitative scenario characteristics, as outlined in the original SRES scenarios. Two scenarios (B1 and B2) also follow (with minor adjustments due to scenario improvements) the original SRES quantifications at the level of 4 and 11 world regions respectively. The quantification of the original SRES A2 scenario has been revised to reflect recent changing perceptions on the demographic outlook of world population growth. In this revised “high population growth” scenario, A2r world population reaches some 12 billion by 2100 (as opposed to some 15 billion in the original SRES A2 scenario) and is characterized by a “delayed fertility transition” that is also mirrored in a delayed (economic) development catch-up, resulting in an initially stagnating and subsequently only very slow reduction in income disparities. The spatially explicit scenario interpretation proceeds via two steps. Through a combination of decomposition and optimization methods, world regional scenario results are first disaggregated to the level of 185 countries. In a subsequent second step, national results are further disaggregated to a grid cell level, taking urbanization and regional (rural–urban) income disparities explicitly into account. A distinguishing feature of the spatially explicit scenario results reported here is that both methodologies, as well as numerical assumptions underlying the “downscaling” exercise, are scenario-dependent, leading to distinctly different spatial patterns of population and economic activities across the three scenarios examined.     

State income tax policy and geographic labour force mobility in the United States

"This study empirically investigates the impact of state income tax policy on U.S. interstate migration [of the labor force] for the period 1985-89. It finds that people vote with their feet and prefer to move so as to minimize their state income tax liabilities."     

EXPLORING THE USEFULNESS OF A NONRANDOM HOLDOUT SAMPLE FOR MODEL VALIDATION: WELFARE EFFECTS ON FEMALE BEHAVIOR*

A particularly challenging use of decision‐theoretic models in economics is to forecast the impact of large changes in the environment. The problem we explore in this article is how to gain confidence in a model's ability to predict the impact of such large changes. We show that an approach to validation and model selection that includes the choice of a “nonrandom holdout sample,” a sample that differs significantly from the estimation sample along the policy dimension that the model is meant to forecast, can be fruitful.     

Cycle and Trend in Models of the Range of Equilibria

This paper investigates the potential of models of the range of equilibria to yield a pattern of equilibrium rates of unemployment that is consistent with the observed mix of cycle with no trend in the rate of unemployment. To do this the paper considers a model in which wages are determined by a group of unionised insiders bargaining with an employer. In the model the supply of labour is endogenous. Specifications of the utility function are found which are consistent with the mix of cycle and no trend in the rate of unemployment. Of these it is concluded that loss aversion in the evaluation of wage relativities is a crucial ingredient for models of the range of equilibria.     

Market Size, Trade, and Productivity

We develop a monopolistically competitive model of trade with firm heterogeneity—in terms of productivity differences—and endogenous differences in the "toughness" of competition across markets—in terms of the number and average productivity of competing firms. We analyse how these features vary across markets of different size that are not perfectly integrated through trade; we then study the effects of different trade liberalization policies. In our model, market size and trade affect the toughness of competition, which then feeds back into the selection of heterogeneous producers and exporters in that market. Aggregate productivity and average mark-ups thus respond to both the size of a market and the extent of its integration through trade (larger, more integrated markets exhibit higher productivity and lower mark-ups). Our model remains highly tractable, even when extended to a general framework with multiple asymmetric countries integrated to different extents through asymmetric trade costs. We believe this provides a useful modelling framework that is particularly well suited to the analysis of trade and regional integration policy scenarios in an environment with heterogeneous firms and endogenous mark-ups.     

Endogenous Firm Objectives

We analyze the behavior of a monopolistic firm in general equilibrium when the firm's decisions are taken through shareholder voting. We show that, depending on the underlying distribution, rational voting may imply overproduction as well as underproduction, relative to the efficient level. Any initial distribution of shares is an equilibrium, if individuals do not recognize their influence on voting when trading shares. However, when they do, and there are no short–selling constraints, the only equilibrium is the efficient one. With short–selling constraints typically underproduction occurs. It is not market power itself causing underproduction, but the inability to perfectly trade the rights to market power.     

ASSESSING THE EFFECT OF PUBLIC SUBSIDIES ON FIRM R&D INVESTMENT: A SURVEY

This survey examines the empirical literature on the relationship between public R&D subsidies and private R&D investment over the past five decades. The survey reveals a considerable heterogeneity of empirical results that cannot be explained fully by methodological issues. We aim to provide further explanations of the possible causes of that heterogeneity. In particular, we emphasise a set of issues that, in our view, are critical to understanding the potential effect of public R&D subsidies on private R&D spending. Special attention is paid to the dynamic aspects and composition of firm R&D, the constraints faced by the firm (such as financial constraints), and the amount and source of public subsidies. None of these issues have been investigated in depth. We formulate a set of research assumptions to guide future empirical research in this field.     

Elasticities of substitution and complementarity

This paper develops a classification scheme of the many different definitions of elasticities of substitution and complementarity in the production case based on primal and dual representations of technology and their related direct and inverse demand functions, gross and net substitution, elasticity type, and three different basic concepts of substitution and complementarity. The ten elasticities of substitution are derived from the cost, profit, input distance, and revenue functions. All the elasticities are equally valid for single and multi-output technologies. The classic Berndt-Wood dataset is used to show the considerable variation across the elasticities.