The age-productivity gradient: Evidence from a sample of F1 drivers

Estimating the effect of aging on productivity requires clean measures of productivity. Additionally, one needs to control for unobserved heterogeneity at the worker, firm and worker/firm level, to account for the role of experience and to correct for selection bias. We tackle these issues exploiting a panel of Gran Prix Formula One drivers, which provides a unique setting to single out the data requirements needed to credibly estimate the effect of age on productivity. Results robust to the inclusion of worker, firm and match effects show that the age-productivity link has an inverted U-shape profile with a peak at the age of 30-32. The use of repeated cross-sections of individuals also produces consistent results provided that cohort effects are properly accounted for. Relying on team-average measures of productivity makes instead inference harder.     

Structural vs. atheoretic approaches to econometrics

In this paper I attempt to lay out the sources of conflict between the so-called “structural” and “experimentalist” camps in econometrics. Critics of the structural approach often assert that it produces results that rely on too many assumptions to be credible, and that the experimentalist approach provides an alternative that relies on fewer assumptions. Here, I argue that this is a false dichotomy. All econometric work relies heavily on a priori assumptions. The main difference between structural and experimental (or “atheoretic”) approaches is not in the number of assumptions but the extent to which they are made explicit.     

How Does Education Affect the Earnings Distribution in Urban China?*

It is widely believed that investing in education could be an effective strategy to promote higher standards of living and equity. We empirically assess this claim by estimating returns to education across the whole earnings distribution in urban China and find supporting evidence. In particular, we find that returns to education are more pronounced for individuals in the lower tail of the distribution than for those in the upper tail and that returns to education are uniformly larger for women than men. We also find that returns to education increased over time across the whole earnings distribution.     

Wage inequality, technology and trade: 21st century evidence

This paper describes and explains some of the principal trends in the wage and skill distribution in recent decades. Increases in wage inequality started in the US and UK at the end of the 1970s, but are now widespread. A good fraction of this inequality trend is due to technology-related increases in the demand for skilled workers outstripping the growth of their supply. Since the early 1990s, labor markets have become more polarized with jobs in the middle third of the wage distribution shrinking and those in the bottom and top third rising. I argue that this is because computerization complements the most skilled tasks, but substitutes for routine tasks performed by middle wage occupations such as clerks, leaving the demand for the lowest skilled service tasks largely unaffected. Finally, I argue that technology is partly endogenous, for example it has been spurred by trade with China. Thus, trade does matter for changes in the labor market, but through a different mechanism than conventionally thought.     

Is the division of labour limited by the extent of the market? Evidence from French cities

This paper provides supportive evidence to the notion that the division of labour is limited by the extent of the (local) market. We first propose a theoretical model. Its main prediction is that scarce specialists occupations are over-represented in large cities. Using census data for French cities, we find strong empirical support for this prediction.     

Cross-sectional dependence robust block bootstrap panel unit root tests

In this paper we consider the issue of unit root testing in cross-sectionally dependent panels. We consider panels that may be characterized by various forms of cross-sectional dependence including (but not exclusive to) the popular common factor framework. We consider block bootstrap versions of the group-mean (Im et al., 2003) and the pooled (Levin et al., 2002) unit root coefficient DF tests for panel data, originally proposed for a setting of no cross-sectional dependence beyond a common time effect. The tests, suited for testing for unit roots in the observed data, can be easily implemented as no specification or estimation of the dependence structure is required. Asymptotic properties of the tests are derived for T going to infinity and N finite. Asymptotic validity of the bootstrap tests is established in very general settings, including the presence of common factors and cointegration across units. Properties under the alternative hypothesis are also considered. In a Monte Carlo simulation, the bootstrap tests are found to have rejection frequencies that are much closer to nominal size than the rejection frequencies for the corresponding asymptotic tests. The power properties of the bootstrap tests appear to be similar to those of the asymptotic tests.     

Comparing the effectiveness of employment subsidies

This paper examines the implications of different types of employment subsidies for employment, welfare, and inequality. It investigates how these effects depend on what target groups the subsidies address. Our analysis focuses on policies that are “approximately welfare efficient” (AWE), i.e. policies that (a) improve employment and welfare, (b) do not raise earnings inequality and (c) are self-financing. We construct a microfounded, dynamic model of hiring and separations and calibrate it with German data. The calibration shows that hiring vouchers can be AWE, while low-wage subsidies are not AWE. Furthermore, hiring vouchers targeted at the long-term unemployed are more effective than those targeted at low-ability workers.     

Semiparametric and nonparametric estimation of sample selection models under symmetry

This paper considers the semiparametric estimation of binary choice sample selection models under a joint symmetry assumption. Our approaches overcome various drawbacks associated with existing estimators. In particular, our method provides root-n$n$ consistent estimators for both the intercept and slope parameters of the outcome equation in a heteroscedastic framework, without the usual cross equation exclusion restriction or parametric specification for the error distribution and/or the form of heteroscedasticity. Our two-step estimators are shown to be consistent and asymptotically normal. A Monte Carlo simulation study indicates the usefulness of our approaches.     

Firms' relative sensitivity to aggregate shocks and the dynamics of gross job flows

We propose the coefficient of variation as a measure of the cyclical volatility of gross job flows that is immune to trends in net job creation. In addition, we show that this measure is intrinsically related to the importance of aggregate shocks for fluctuations in job flows at the firm level. Using data for the Portuguese economy, we conclude that the coefficient of variation is a more robust measure for the underlying volatility of gross job flows. We also find that large and old firms exhibit higher relative sensitivity to aggregate shocks than small and young firms, and have a disproportional influence over the dynamics of aggregate job reallocation. In particular, since large and old firms tend to reallocate jobs less procyclically than small and young firms, job reallocation is less procyclical than if all firm classes were equally sensitive to aggregate shocks.     

The efficiency of training and hiring with intrafirm bargaining

This paper demonstrates that firms hire and train workers efficiently in a matching and intrafirm bargaining economy when the Hosios condition holds and returns to scale are constant. This conclusion stands in contrast to the prevailing view that training costs are a source of inefficiency in imperfect labor markets. The efficiency of the competitive economy relies on the ability of large firms to take into account the negative impact of the training rate on the wages negotiated inside the firm through intrafirm bargaining: untrained workers accept a wage reduction in compensation for potential training that is accessible only following employment. This intrafirm bargaining process solves efficiency problems associated with training costs that would otherwise lead to inefficient hiring and training decisions. This conclusion holds true for both specific and general human capital.     

Goodness-of-fit tests for conditional models under censoring and truncation

The problem of specification tests for conditional models is studied when the data are subject to left truncation and right censoring. A general method is applied to derive tests for the polynomial regression, the proportional hazards, the additive risks and the proportional odds models. Bootstrap versions to approximate the critical values of the test are introduced and proved to work both from a theoretical viewpoint as well as in a small simulation study.     

Quasi-structural estimation of a model of childcare choices and child cognitive ability production

This article evaluates the effects of maternal vs. alternative care providers’ time inputs on children’s cognitive development using the sample of single mothers in the National Longitudinal Survey of Youth. To deal with the selection problem created by unobserved heterogeneity of mothers and children, we develop a model of mother’s employment and childcare decisions. We then obtain approximate decision rules for employment and childcare use, and estimate these jointly with the child’s cognitive ability production function. To help identify our selection model, we take advantage of the plausibly exogenous variation in employment and childcare choices of single mothers generated by the variation in welfare rules across states and over time created by the 1996 welfare reform legislation and earlier State waivers.