Knowledge that Transforms

We examine the effect of observed and unobserved heterogeneity in the desire to die with positive net worth. Using a structural life-cycle model nested in a switching regression with unknown sample separation, we find that roughly three-fourths of the elderly single population has abequest motive. Both the presence and the magnitude of the bequest motive are statistically and economically significant. On average, households with a bequest motive spend about 25% less on consumption expenditures. We conclude that, among the elderly single households in our sample, about four-fifths of their net wealth will be bequeathed and approximately half of this is due to a bequest motive. Copyright 2007, Wiley-Blackwell.

This paper presents a theory of location choice that draws on insights from the incomplete contracts and investment flexibility (real option) literatures. Our analysis indicates that the choice of locating within rather than away from industry clusters is influenced by the extent to which training costs are borne by firms versus employees. In addition, the uncertainty about future productivity shocks and the ability of firms to modify the scale of their operations also influence location choice. In particular, we show that locating in clusters is preferred when training costs are borne by workers and when firm-specific productivity shocks can potentially be large. However, there is an incentive for firms to choose isolated locations when significant training costs are borne by firms.

This paper examines the role of peer effects in teenagers' smoking behaviour in the U.S.A. I present a random utility model that incorporates complementarity between individual and peer smoking. A Markov process model of smoking interactions between individuals is presented. I estimate the structural parameters of the model using a steady-state distribution that is determined by the Markov process. The empirical results strongly support the presence of positive peer effects. Interestingly, peer interactions are found to be stronger within the same gender than across genders. The same result is found for race. Moreover, a multiplier effect is found. Copyright 2007, Wiley-Blackwell.

Understanding the accumulation of match-specific capital is crucial in shedding light on the reasons for the prevalence of long-term employment relationships and on the welfare consequences of turnover in the labour market. One of the most important sources of match-specific capital is human capital acquired through match-specific learning. Such learning can take on two distinct forms. In the first case, workers accumulate match-specific human capital through learning by doing. In the second case, a worker and a firm in an employment relationship learn about the quality of the match over time, thereby acquiring valuable information. I construct a structural model that embeds these two learning explanations and show that it is possible to distinguish the two by using turnover data on employing firms coupled with data on workers. I use a French matched employer—employee data-set to estimate the structural model using the Efficient Method of Moments, a simulation-based estimation method. I find that, while learning by doing may be present during the first six months of an employment relationship, learning about match quality dominates at longer tenures. This finding has important consequences for the understanding of the sources of match-specific capital and for the desirability of policies that alter the incentives for turnover for workers of different tenure. Copyright 2007, Wiley-Blackwell.

The aim of this paper is to analyse the impact of heterogeneous beliefs in an otherwise standard competitive complete market economy. The construction of a consensus probability belief, as well as a consensus consumer, is shown to be valid modulo an aggregation bias, which takes the form of a discount factor. In classical cases, the consensus probability belief is a risk tolerance weighted average of the individual beliefs, and the discount factor is proportional to beliefs dispersion. This discount factor makes the heterogeneous beliefs setting fundamentally different from the homogeneous beliefs setting, and it is consistent with the interpretation of beliefs heterogeneity as a source of risk. We then use our construction to rewrite in a simple way the equilibrium characteristics (market price of risk, risk premium, risk-free rate) in a heterogeneous beliefs framework and to analyse the impact of beliefs heterogeneity. Finally, we show that it is possible to construct specific parametrizations of the heterogeneous beliefs model that lead to globally higher risk premia and lower risk-free rates.

A Welfare-to-Work (WTW) program is a mix of government expenditures on various labour market policies targeted to the unemployed (e.g. unemployment insurance (UI), job search monitoring (JM), social assistance (SA), wage subsidies). This paper provides a dynamic principal—agent framework suitable for analysing chief features of an optimal WTW program, such as the sequence and duration of the different policies, the dynamic pattern of payments along the unemployment spell, and the emergence of taxes/subsidies upon re-employment. The optimal program endogenously generates an absorbing policy of last resort (“social assistance”) characterized by a constant lifetime payment and no active participation by the agent. Human capital depreciation is a necessary condition for policy transitions to be part of an optimal WTW program. The typical sequence of policies is quite simple: the program starts with standard UI, then switches into monitored search and, finally, into SA. The optimal benefits are decreasing during unemployment insurance and constant during both JM and SA. Whereas taxes (subsidies) can be either increasing or decreasing with duration during UI, they must decrease (increase) during a phase of JM. In a calibration exercise, we use our model to analyse quantitatively the features of the optimal program for the U.S. economy. With respect to the existing U.S. system, the optimal WTW scheme delivers sizeable welfare gains to unskilled workers because the incentives to search for a job can be retained even while delivering more insurance and using costly monitoring less intensively.

This paper studies moral hazard in teams using a model where efforts are promoted via the combination of profit shares and relational contracts. The focus is on how these two forms of incentives interact. According to the degree of effort observability and the importance of future interaction, the optimal allocation of profit shares can range from a wide dispersion across players to a full concentration of shares in the hands of a single player. When shares are sufficiently concentrated, the corresponding residual claimant can also adopt the role of administering all relational contracts, therefore serving as an endogenously chosen principal.

Most economic activity occurs in cities. This creates a tension between local increasing returns, implied by the existence of cities, and aggregate constant returns, implied by balanced growth. To address this tension, we develop a general equilibrium theory of economic growth in an urban environment. In our theory, variation in the urban structure through the growth, birth, and death of cities is the margin that eliminates local increasing returns to yield constant returns to scale in the aggregate. We show that, consistent with the data, the theory produces a city size distribution that is well approximated by Zipf's law, but that also displays the observed systematic underrepresentation of both very small and very large cities. Using our model, we show that the dispersion of city sizes is consistent with the dispersion of productivity shocks found in the data.

This paper presents a test for exogeneity of explanatory variables that minimizes the need for auxiliary assumptions that are not required by the definition of exogeneity. It concerns inference about a non-parametric function g that is identified by a conditional moment restriction involving instrumental variables (IV). A test of the hypothesis that g is the mean of a random variable Y conditional on a covariate X is developed that is not subject to the ill-posed inverse problem of non-parametric IV estimation. The test is consistent whenever g differs from E (Y ∣ X) on a set of non-zero probability. The usefulness of this new exogeneity test is displayed through Monte Carlo experiments and an application to estimation of non-parametric consumer expansion paths.

In this paper, a formal test of intra-household commitment is derived and performed. To that end, two models of household intertemporal behaviour are developed. In both models, household members are characterized by individual preferences. In the first formulation, household decisions are always on the ex ante Pareto frontier. In the second model, the assumption of intra-household commitment required by ex ante efficiency is relaxed. It is shown that the full-efficiency household Euler equations are nested in the no-commitment Euler equations. Using this result, the hypothesis that household members can commit to future allocations of resources is tested using the Consumer Expenditure Survey. I strongly reject this hypothesis. It is also shown that the standard unitary framework is a special case of the full-efficiency model. However, if household members are not able to commit, household intertemporal behaviour cannot be characterized using the standard life-cycle model. These findings have two main implications. First, policy makers can change household behaviour by modifying the decision power of individual household members. Second, to evaluate programmes designed to improve the welfare of household members, it would be beneficial to replace the standard unitary model with a characterization of household behaviour that allows for lack of commitment. Copyright 2007, Wiley-Blackwell.