There is a substantial empirical literature quantifying the positive relationship between city size and productivity. The paper draws out the implications of this productivity relationship for evaluations of urban transport improvements. A theoretical model is developed and used to derive a...

We conducted a survey covering 20% of villages with 200-1000 population in rural Guinea-Bissau. We interviewed household heads, care-givers of children, and their teachers and schools. We analysed results from 9,947 children, aged 7-17, tested for literacy and numeracy competency. Only 27% of...

This chapter discusses whether and how .new quantitative trade models.(NQTMs) can be fruitfully applied to quantify the welfare effects of trade liberalization, thus shedding light on the trade-related effects of further European integration. On the one hand, it argues that NQTMs have indeed the...

This paper presents a pairwise matching model with two-sided information asymmetry to analyse the impact of information costs on endogenous network building and matching by information intermediaries. The framework innovates by examining the role of information costs on incentives for trade...

A two-sided, pair-wise matching model is developed to analyse the strategic interaction between two information intermediaries who compete in commission rates and network size, giving rise to a fragmented duopoly market structure. The model suggests that network competition between information...

Although economists have long been aware of Jensen's inequality, many econometric applications have neglected an important implication of it: the standard practice of interpreting the parameters of log-linearized models estimated by ordinary least squares as elasticities can be highly misleading...

We use a new firm level data set that establishes the location, ownership, and activity of 650,000 multinational subsidiaries—close to a comprehensive picture of global multinational activity. A number of patterns emerge from the data. Most foreign direct investment (FDI) occurs between rich...

We extend the simulation results given in Santos-Silva and Tenreyro (2006, 'The Log of Gravity', The Review of Economics and Statistics, 88, pp.641-658) by considering data generated as a finite mixture of gamma variates. Data generated in this way can naturally have a large proportion of zeros...

Studies of firm-level data have shown that there is a huge dispersion of productivity across firms even when industries are narrowly defined. So there is a significant opportunity for the least productive firms to catch up to the most productive. The formers' convergence could therefore...

Helpman, Melitz, and Rubinstein (2008)-HMR-present a rich theoretical model to study the determinants of bilateral trade flows across countries. The model is then empirically implemented through a two-stage estimation procedure. This note seeks to clarify some econometric aspects of the...