基于极值分布的离散选择模型尺度参数 - 交通运输工程学报.pdf

第9 卷　第1期 交 通 运 输 工 程 学 报 Vol.9　No.1 2009 年2 月 Journal of Traffic and Transportation Engineering Feb.2009 :1671-1637(2009)01-0092-04 1 2 郑　柯 ,郑　勇 (1. , 　410082;2., 　030006) 　:为了准确把握尺度参数在模型建模、分 以及应用过程中的作用, 以基于极值分布的 ultinomial Logit 模型和Nested Logit 模型为研究对象, 从建模的基础———误差项的分布形式入 手,通过模型形式和误差项性质两方面研究了尺度参数在两种模型中的特性,并对其进行了对比分 。分 结果表明:尺度参数不仅限制了模型效用函数的尺度,而且也反映了误差项的方差水平, 但 对于以上两种不同的模型,其在尺度限制、误差项方差水平及独立性、自身取值范围等方面均表现出 不同的特性, ultinomial Logit模型的尺度参数反映了有关整 个效用确定项的误差项方差水平, 而 Nested Logit模型的尺度参数只是反映了与某一选择枝有关的部分效用确定项的误差项方差水平。 :交通规划;离散选择模型;Logit 模型;Nested Logit 模型;尺度参数 :U491.1　　　:A Scaleparameter of discrete choice model basedon extremevalue distribution 1 2 ZHENG Ke , ZHENG Yong (1.School of Civil Engineering, Hunan University, Changsha 410082, Hunan, China; 2.Shanxi Provincial Research Institute of Communications, Taiyuan 030006, Shanxi, China) Abstract:In order to understand the role of scale parameter in the process of modeling, analysis and application, multinomial logit model and nested logit model were discussedbased on extreme value distribution.Starting with the distribution of error terms, the properties of scale parameter in two models were studied in aspects of model expressions and error term properties, and a comparison analysis was made.Analysis result shows that scale parameter not only restricts the scale of utility function, but also reflects the variance of error terms.However, it reveals different properties at two different models in terms of scale restriction, variance and independence degree of error terms, and numerical areas.For multinomial logit model, the scale paramete