Browsing by Author "Ortuzar, J. de D."

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    Thresholds and indifference in stated choice surveys
    (PERGAMON-ELSEVIER SCIENCE LTD, 2010) Cantillo, Victor; Amaya, Johanna; Ortuzar, J. de D.
    One typical aim of choice experiment designs is utility balance, that is, the alternatives defined within each choice set should have similar choice probabilities; otherwise, choice is too easy and little information about preferences may be obtained. Therefore, in a good design respondents may often find themselves close to indifference and thus perception thresholds may be an issue. We propose a discrete choice model to examine the behaviour of individuals with indifference thresholds, i.e. that would make them perceive two or more alternatives as almost identical in stated choice (SC) experiments. Such thresholds may be stochastic, differ among the population and even be a function of socio-economic characteristics and choice conditions. Two estimate this model we need SC data including an "indifference option", so that respondents are not forced to choose when finding that the two alternatives are equally attractive. Our formulation allows estimating the parameters of a threshold probability distribution using information about choices. As an illustration, the model is applied both to synthetic and real data; results clearly show that when indifference thresholds exist, using models without them can lead to errors in estimation and prediction. (C) 2009 Elsevier Ltd. All rights reserved.
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    Understanding the differences between car and motorcycle ownership. The case of Bogota, Colombia
    (2024) Rodriguez-Valencia, Alvaro; Ortuzar, J. de D.; Mesa-Garcia, Santiago
    Motorcycle and car ownership are rapidly growing in the Global South. However, little research has been conducted to understand the factors influencing motorcycle ownership and whether they differ from those affecting car ownership. In this paper, we explore and explain the similarities and differences between the factors that influence the decision to own both types of private vehicles in Bogota, Colombia. Using information from the 2019 Household Travel Survey and open land-use information of Bogota, we formulate and estimate two independent discrete choice models for car ownership and motorcycle ownership. Our results indicate that the factors influencing the decision to own a car are indeed not the same as those influencing the decision to own a motorcycle. First, we found that sociodemographic variables do not keep the same sign, magnitude, or meaning in both types of ownership models. However, the main difference between the two specifications is associated with spatial-related (geographic) variables. Mixed land uses, density, and proximity to mass transit seems to affect car ownership, while living in the periphery of the city increases the likelihood of owning a motorcycle. Our findings provide evidence about a topic that is essential in transportation demand models for mobility plans, especially in the Global South. They also highlight the need for further research focusing on motorcycle ownership.