Selection Bias in Value of Travel Time Savings

Abstract

In this paper we investigate the value of travel time savings. Estimation of this is in most cases based on samples using a specific mode. We use a mixed logit model to estimate the VTTS together with an auxiliary probit equation to capture the fact that the sample is non random. The results show that the probit equation in some cases gives extra information that can be used to improve the VTTS estimates from the mixed logit model. Hence this opens a way to investigate the possible selection bias in standard estimations of VTTS.