Talvitie, AnttiKirshner, Daniel1980-01-302020-05-202022-11-252020-05-202022-11-251978https://orlis.difu.de/handle/difu/431606Three problems of great importance to urban travel demand modeling using multinominal logit models are examined in this paper. They are (1) the effect of data outliers on model coefficients; (2) the effect of model specification on coefficients and model explanatory power; and (3) the transferability of model coefficients within the region, between regions, and in time. Four data sets are used in the study. They are Washington, D. C., Minneapolis-St. Paul, and two data sets from the San Francisco Bay Area, Pre-BART and Post-BART. The data are standard home-interview survey data appended with network supplied modal travel cost and time information. The findings of the research are occasionally contradictory; the majority of the evidence supports the following conclusions. The ,,outliers'' do not have a statistically significant effect (at 0.05 level) on the coefficients; however, the outliers can have a substantial effect on the point estimates of the coefficients. Model specification has an impact on model coefficients and model explanatory power. In particular, the definition of out-of-vehicle travel time appears to be important and, if available, the use of separate walk and wait times is prefered over their sum, the out-of-vehicle time. Finally, the model coefficients do not appear transferable within region, between regions, or in time.VerkehrstheorieModellStadtverkehrZeitschriftenaufsatz005749