Semiparametric estimation of a work-trip mode choice model

A binary response model of choice between automobile and transit for travel to work is estimated using fixed- and random-coefficients probit specifications, a semiparametric single-index specification, and a semiparametric specification that permits arbitrary heteroskedasticity of 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 arbitrarily heteroskedastic model. Specification tests result in rejection of the fixed- coefficients probit and single-index models but not of the random-coefficients probit model and the semiparametric model with arbitrary heteroskedasticity.