Retirement and Healthy Eating

This paper investigates the effect of retirement on healthy eating using data drawn from the Survey of Health, Ageing and Retirement in Europe (SHARE). We estimate the causal effect of retiring from work on daily fruit or vegetable consumption by exploiting policy changes in eligibility rules for early and statutory retirement. Our results show that changes in eating behaviour upon retirement are gender-specific: retirement induces men to reduce healthy eating; it has no effect on women. We further show that, for men, retirement increases the probability of becoming obese.     

Fast and accurate calculation of American option prices

We propose a very efficient numerical method to solve a nonlinear partial differential problem that is encountered in the pricing of American options. In particular, by using the front-fixing approach originally developed in Wu and Kwok (J Financ Eng 6:83–97, 1997) and Nielsen et al. (J Comput Finance 5:69–97, 2002) in conjunction with a suitable change of the time variable, a (nonlinear) partial differential problem is obtained which can be solved very efficiently by means of a finite difference scheme enhanced by repeated Richardson extrapolation. Numerical results are presented showing that the novel algorithm yields excellent results, and performs significantly better than a finite different method with Bermudan approximation.     

Worker absenteeism and incentives: evidence from Italy

In Italy, employees are fully insured against earning losses due to illness. Since worker's health is not easily verifiable, absenteeism due to illness is considered an empirical proxy for employee shirking. The Bank of Italy Household Survey (SHIW) provides individual data on days of absence. Controlling for personal characteristics and potential determinants of health status and family responsibilities (age, gender, education, marital status, children at home), we show that the nature of employment contracts affects workers' incentives to provide effort: sickness absences, at least partially, hide opportunistic behaviours. The type of occupation and the labour contracts affects workers' behaviour in that more protected and difficult to monitor jobs show significantly higher levels of absenteeism: employees in public sector or in large firms, with permanent contracts or with longer tenure, individuals living in regions with low unemployment rates. Copyright © 2010 John Wiley & Sons, Ltd.     

On the anti-competitive effects of quantity discounts

We analyze the competitive effects of quantity discounts in an asymmetric duopoly. We find that for a sizeable set of parameter values, quantity discounts harm the smaller firm and reduce consumers' surplus. They can even decrease social welfare, i.e. the sum of producers' and consumers' surpluses. However, the circumstances in which quantity discounts may decrease social welfare are limited and difficult to identify in practice.     

Competition, human capital and income inequality with limited commitment

We develop a dynamic model with two-sided limited commitment to study how barriers to competition, such as restrictions to business start-up and non-competitive covenants, affect the incentive to accumulate human capital. When contracts are not enforceable, high barriers lower the outside value of ‘skilled workers’ and reduce the incentive to accumulate human capital. In contrast, low barriers can result in over-accumulation of human capital. This can be socially optimal if there are positive spillovers. A calibration exercise shows that this mechanism can account for a sizable portion of cross-country income inequality.     

Essential equilibria of discontinuous games

We introduce spaces of discontinuous games in which games having essential Nash equilibria are the generic case. In order to prove the existence of essential Nash equilibria in such spaces, we provide new results on the Ky Fan minimax inequality. In the setting of potential games, we show that games with essential Nash equilibria are the generic case when their potentials satisfy a condition called weak upper pseudocontinuity that is weaker than upper semicontinuity.     

Identifying and treating outliers in finance

Outliers represent a fundamental challenge in the empirical finance research. We investigate whether the routine techniques used in finance research to identify and treat outliers are appropriate for the data structures we observe in practice. Specifically, we propose a multivariate identification strategy that can effectively detect outliers. We also introduce an estimator that minimizes the bias outliers caused in both cross‐sectional and panel regressions and provide outlier mitigation guidance. Using replications of four recently published studies in premier finance journals, we show how adjusting for multivariate outliers can lead to significantly different results.