SEMIPARAMETRIC ESTIMATION OF A WORK-TRIP MODE CHOICE MODEL

A binary response model of choice between automobile and transit for t ravel to work is estimated using fixed- and random-coefficients probit specifications, a semiparametric single-index specification, and a se miparametric specification that permits arbitrary heteroskedasticity o f unknown form. The estimation methods are maximum likelihood for the probit models, semiparametric quasi-maximum-likelihood for the single- index model, and maximum score and smoothed maximum score for the arbi trarily heteroskedastic model. Specification tests result in rejection of the fixed-coefficients probit and single-index models but not of t he random-coefficients probit model and the semiparametric model with arbitrary heteroskedasticity.