Productivity is high in cities partly because the urban environment acts as a self-selection mechanism.  If workers have imperfect information about the quality of workers with whom they match and matches take place within cities, then high-ability workers will choose to live and work in...

This paper argues that government should pay greater heed to recruitment and retention when designing performance measurement systems for bureaucracies. In the face of pervasive rigidities in public sector pay, internal performance measurement rewards quitters and scars stayers and therefore...

High frequency financial data allows us to learn more about volatility, volatility of volatility and jumps.  One of the key techniques developed in the literature in recent years has been bipower variation and its multipower extension, which estimates time-varying volatility robustly to...

We consider three 'cases studies' of the uses and mis-uses of mathematics in economics and econometrics.  The first concerns economic forecasting, where a mathematical analysis is essential, and is independent of the specific forecasting model and how the process being forecast behaves.  The...

Almost no economic time series is either weakly or strictly stationary: distributions of economic variables shift over time.  Thus, the present treatment of expectations in economic theories of inter-temporal optimization is inappropriate.  It cannot be proved that conditional expectations...

We reconsider the job design theory of Holmstrom and Milgrom (1991), to include career concerns considerations. When reputations are considered, discretion may play a more integral part of the incentive scheme. It can be a useful instrument to enhance incentives and prevent the adverse selection...

A multinomial choice framework is used to investigate the nature of women`s transitions between full-time employment, part-time employment and non-employment. The stochastic framework allows time varying and time invariant unobserved preferences, and also controls for the possible endogenity of...

A common theme in the theory of demand aggregation is that market demand can acquire properties which are not always individually present among the agents who make up that market, a phenomenon we call heterosis in this paper. This paper focusses on the well known result that with a suitable...