We consider the estimation of the usual Gravity model of trade, which involves flows of trade, say exports, from country i to country j in time period t. We suggest an easy-to-implement generalised method of moments estimator that avoids the issues associated with the usual fixed effects...

Obesity is a major risk factor for several diseases including diabetes, heart disease and stroke. Increasing rates of obesity internationally are set to cost health systems increasing resources. In the US a conservative estimate puts resources already spent on obesity at $120 billion annually....

This paper focuses on the self-reported responses given to survey questions of the form In general how would you rate your health? with typical response items being on a scale ranging from poor to excellent. Usually, the overwhelming majority of responses fall in either the middle category or...

We explore practical methods of carrying out Lagrange Multiplier tests for variance components in two models in which the derivatives needed for the test are identically zero at the restricted estimates, the random effects probit model and the stochastic frontier model. The techniques are...

The most familiar fixed effects (FE) and random effects (RE) panel data treatments for count data were proposed by Hausman, Hall and Griliches (HHG) (1984). The Poisson FE model is particularly simple and is one of a small few known models in which the incidental parameters problem is, in fact,...

We consider a bivariate Poisson model that is based on the lognormal heterogeneity model. Two recent applications have used this model. We suggest that the correlation estimated in their model frameworks is an ambiguous measure of the correlation of the variables of interest, and may...

This study presents several extensions of the most familiar models for count data, the Poisson and negative binomial models. We develop an encompassing model for two well known variants of the negative binomial model (the NB1 and NB2 forms). We then propose some alternative approaches to the...

We detail the basic theory for models of discrete choice. This encompasses methods of estimation and analysis of models with discrete dependent variables. Entry level theory is presented for the practitioner. We then describe a few of the recent, frontier developments in theory and practice

Heckman s (1979) sample selection model has been employed in three decades of applications of linear regression studies. The formal extension of the method to nonlinear models, however, is of more recentvintage. A generic solution for nonlinear models is proposed in Terza (1998). We have...

The normal-gamma stochastic frontier model was proposed in Greene (1990) and Beckers and Hammond (1987) as an extension of the normalexponential proposed in the original derivations of the stochastic frontier byAigner, Lovell, and Schmidt (1977). The normal-gamma model has the virtue ofproviding...