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Titolo:
Confidence intervals to bound the value of time
Autore:
Armstrong, P; Garrido, R; Ortuzar, JD;
Indirizzi:
Pontificia Univ Catolica Chile, Dept Transport Engn, Santiago 22, Chile Pontificia Univ Catolica Chile Santiago Chile 22 ngn, Santiago 22, Chile
Titolo Testata:
TRANSPORTATION RESEARCH PART E-LOGISTICS AND TRANSPORTATION REVIEW
fascicolo: 2-3, volume: 37, anno: 2001,
pagine: 143 - 161
SICI:
1366-5545(200104/07)37:2-3<143:CITBTV>2.0.ZU;2-G
Fonte:
ISI
Lingua:
ENG
Soggetto:
MODE CHOICE MODELS;
Keywords:
value of time; confidence interval; discrete choice;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Social & Behavioral Sciences
Engineering, Computing & Technology
Citazioni:
24
Recensione:
Indirizzi per estratti:
Indirizzo: Ortuzar, JD Pontificia Univ Catolica Chile, Dept Transport Engn, Casilla 306,Codigo 105, Santiago 22, Chile Pontificia Univ Catolica Chile Casilla 306,Codigo 105 Santiago Chile 22
Citazione:
P. Armstrong et al., "Confidence intervals to bound the value of time", TRANSP R E, 37(2-3), 2001, pp. 143-161

Abstract

The derivation of a subjective value of time (SVT) requires finding the marginal rate of substitution between travel time and cost in a travel choicemodel. In the typical case of models with linear-in-parameters utility functions, the SVT is equal to the ratio between the parameters of travel timeand cost. However, since model estimation yields an estimator of the true values of their parameters (with a certain probability distribution), the computed SVT is also an estimator with another probability distribution; then, it is important to devise a method to incorporate the randomness of the estimated SVT in project evaluation. In this paper, we consider this problem rigorously and propose methods to replace the typical SVT point estimatesby the construction of confidence intervals for a certain probability level. This allows, in addition, to estimate the SVT limits (lower and upper) which may be used in sensitivity analyses of the calculation of project revenues in transport infrastructure investment. The paper proposes two forms for building these intervals: the t-test and the LR-test, and discusses the construction of intervals for Multinomial Logit (MNL), Hierarchical Logit (HL) and Box-Cox Logit (BCL) models. We use two samples where the values of the level-of-service attributes have been measured with an unusually high degree of precision. Other methods proposed in the literature are also studied (simulation of multivariate normal variates (MVNS), SVT normal approximation (NA), and re-sampling techniques) using the above data, and their advantages and disadvantages are analysed. In addition, the effects of different modelling elements on the size and quality of the constructed intervals are scrutinised, such as model specification, sample size and individual income. Finally, the proposed methods are compared and recommendations about the use of each one in practice are indicated. (C) 2001 Elsevier Science Ltd. All rights reserved.

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Documento generato il 05/04/20 alle ore 07:12:48