Growth in economies with non convexities: sunspots and lottery equilibria

Summary. We investigate the relation between lotteries and sunspot allocations in a dynamic economy where the utility functions are not concave. In an intertemporal competitive economy, the household consumption set is identified with the set of lotteries, while in the intertemporal sunspot economy it is the set of measurable allocations in the given probability space of sunspots. Sunspot intertemporal equilibria whenever they exist are efficient, independently of the sunspot space specification. If feasibility is, at each point in time, a restriction over the average value of the lotteries, competitive equilibrium prices are linear in basic commodities and intertemporal sunspot and competitive equilibria are equivalent. Two models have this feature: Large economies and economies with semi-linear technologies. We provide examples showing that in general, intertemporal competitive equilibrium prices are non-linear in basic commodities and, hence, intertemporal sunspot equilibria do not exist. The competitive static equilibrium allocations are stationary, intertemporal equilibrium allocations, but the static sunspot equilibria need not to be stationary, intertemporal sunspot equilibria. We construct examples of non-convex economies with indeterminate and Pareto ranked static sunspot equilibrium allocations associated to distinct specifications of the sunspot probability space.Received: 25 August 2003, Revised: 16 March 2004, JEL Classification Numbers: D84, D90.Correspondence to: Paolo SiconolfiWe thank Herakles Polemarchakis for helpful conversations on the topic. The research of Aldo Rustichini was supported by the NSF grant NSF/SES-0136556.     

Moonlighting politicians

In most modern democracies elected officials can work in the private sector while appointed in parliament. We show that when the political and market sectors are not mutually exclusive, a trade-off arises between the quality of elected officials and the time they devote to political life. If high-ability citizens can keep earning money outside of parliament, they will be more likely to run for election; for the same reason, they will also be more likely to shirk once elected. These predictions are confronted with a dataset about members of the Italian Parliament from 1996 to 2006. The empirical evidence shows that bad but dedicated politicians come along with good but not fully committed politicians. There is in fact a non-negligible fraction of citizens with remarkably high pre-election income who are appointed in parliament. These citizens are those who gain relatively more from being elected in terms of outside income. At the same time, they are less committed to the parliamentary activity in terms of voting attendance.     

Minimum income in a transition economy

The Albanian Ndihma Ekonomike is one of the first poverty reduction programmes launched in transitional economies. Its record has been judged positively during the recession period of the 1990s and negatively during the more recent growth phase. This article reconsiders the programme using a regression‐adjusted local linear matching estimator first suggested by Heckman et al. (1997, 1998). We find the programme to have a weak targeting capacity and a non‐significant impact on different household outcomes.     

The returns to formality and informality in urban Africa

This paper addresses the questions as to the size and causes of earnings differentials in two urban African labor markets, those of Ghana and Tanzania. We have panel data so we can ask how far time invariant unobservables, market ability for short, matters in the determination of earnings. We also have information on whether the individual is own self-employed, self-employed with employees, a private or public sector wage employee and the size of the enterprise in which wage employees work or which the self-employed owns. We find, mirroring work on developed economies, that unobserved individual market ability is by far the most important factor explaining the variance of earnings. With controls for such ability the gap between private wage employment and civil servants is about 50%. With controls for enterprise size we find that wage employees earn the same as the self-employed in both Ghana and Tanzania. Enterprise size matters. At most half of the OLS effect of size on earnings can be explained by unobservable ability. Workers in the largest firms are the high earners with wage rates which exceed those of civil servants. These results all assume exogenous movement. We find evidence that endogeneity bias may be serious and may be understating the extent of both the size effect and the private sector wage (negative) premium. The implications of our results for understanding the nature of formal and informal employment in Africa are discussed.     

The co-evolution of innovation,demand and growth

In order to explain long-run economic development, we analyse in this paper the interplay between supply-side and demand-side processes. On the supply side, three different innovation processes are observed and interact: (i) growing productive efficiency, (ii) the emergence of new sectors and (iii) the increasing quality and differentiation of existing products. On the demand side, we analyse the meaning of disposable income and varying preference systems. The analysis is undertaken with the help of a numerical model of economic growth by the emergence of new industries. Our results show that the time path of economic development which we observe could not have been generated by taking into account a supply-side-based view on innovations alone. Without making reference to the formation of an adequate demand, development processes cannot be explained. The three processes need to be combined because each one individually would not suffice to generate long-run economic development. However, only with the formation of an adequate demand long-run economic development becomes sustainable.     

HEALTH IMPROVEMENTS AND THE TRANSITION OUT OF MALTHUSIAN STAGNATION

The central component of most economic models that analyse the transition from the Malthusian regime to self-sustaining developed economies is education. Improved health is normally envisaged as simply a by-product of economic growth. Whereas growth does, indeed, tend to improve health status, the reverse is also true, namely that health improvements are a dynamic force capable of driving economic expansion. This paper underlines the importance of health improvements in escaping from Malthusian stagnation. Further, and in contrast to existing literature, which emphasizes the effects of changes in mortality rates, this paper focuses on the relationship between health status and the efficiency of human capital technology. Through this channel, health improvements stimulate investments in child quality in terms of both nourishing and schooling and drive the economy towards the Modern Growth regime.     

RELAXED UTILITY MAXIMIZATION IN COMPLETE MARKETS

For a relaxed investor—one whose relative risk aversion vanishes as wealth becomes large—the utility maximization problem may not have a solution in the classical sense of an optimal payoff represented by a random variable. This nonexistence puzzle was discovered by Kramkov and Schachermayer (1999) , who introduced the reasonable asymptotic elasticity condition to exclude such situations. Utility maximization becomes well posed again representing payoffs as measures on the sample space, including those allocations singular with respect to the physical probability. The expected utility of such allocations is understood as the maximal utility of its approximations with classical payoffs—the relaxed expected utility. This paper decomposes relaxed expected utility into its classical and singular parts, represents the singular part in integral form, and proves the existence of optimal solutions for the utility maximization problem, without conditions on the asymptotic elasticity. Key to this result is the Polish space structure assumed on the sample space.