In this paper, we explore the properties of a positive-part Stein-like estimator which is a stochastically weighted convex combination of a fully correlated parameter model estimator and uncorrelated parameter model e...In this paper, we explore the properties of a positive-part Stein-like estimator which is a stochastically weighted convex combination of a fully correlated parameter model estimator and uncorrelated parameter model estimator in the Random Parameters Logit (RPL) model. The results of our Monte Carlo experiments show that the positive-part Stein-like estimator provides smaller MSE than the pretest estimator in the fully correlated RPL model. Both of them outperform the fully correlated RPL model estimator and provide more accurate information on the share of population putting a positive or negative value on the alternative attributes than the fully correlated RPL model estimates. The Monte Carlo mean estimates of direct elasticity with pretest and positive-part Stein-like estimators are closer to the true value and have smaller standard errors than those with fully correlated RPL model estimator.展开更多
Since land and labor force are primary resources to be used and controlled by rural households, the allocation of labor forces will influence land uses, and further lead to land use conversion. The present study used ...Since land and labor force are primary resources to be used and controlled by rural households, the allocation of labor forces will influence land uses, and further lead to land use conversion. The present study used the Binary Logit model to investigate the influence of labor force transfer, characteristics of rural households, location, and land market on agricultural land use conversion at rural household level. This study was conducted based on 329 valid questionnaires, which were obtained in Changshu, Rudong, and Tongshan counties, respectively representing the southern, middle and northern areas of Jiangsu Province. The results showed that land market participation, location, zonal difference and labor transfer had strong influences on agricultural land use conversion. The participation of land market had a strong positive effect on land use conversion, especially for the farmland converted to the fishpond. The nearer to the county seat, the more conversion of land use occurred. Particularly, the labor force transfer caused by wage employment decreased this conversion probability, while the labor transfer caused by self-employment led to more conversion; and the increasing of income from labor transfer increased the conversion. Moreover, land use con- versions demonstrated zonal difference, which were more in Rudong and Changshu counties than in Tongshan County, and the factors influencing this conversion were different in the three regions.展开更多
The need for travel demand models is growing worldwide. Obtaining reasonably accurate level of service (LOS) attributes of different travel modes such as travel time and cost representing the performance of transporta...The need for travel demand models is growing worldwide. Obtaining reasonably accurate level of service (LOS) attributes of different travel modes such as travel time and cost representing the performance of transportation system is not a trivial task, especially in growing cities of developing countries. This study investigates the sensitivity of results of a travel mode choice model to different specifications of network-based LOS attributes using a mixed logit model. The study also looks at the possibilities of correcting some of the inaccuracies in network-based LOS attributes. Further, the study also explores the effects of different specifications of LOS data on implied values of time and aggregation forecasting. The findings indicate that the implied values of time are very sensitive to specification of data and model implying that utmost care must be taken if the purpose of the model is to estimate values of time. Models estimated on all specifications of LOS-data perform well in prediction, likely suggesting that the extra expense on developing a more detailed and accurate network models so as to derive more precise LOS attributes is unnecessary for impact analyses of some policies.展开更多
In this paper,we study optimal model averaging estimators of regression coefficients in a multinomial logit model,which is commonly used in many scientific fields.A Kullback-Leibler(KL)loss-based weight choice criteri...In this paper,we study optimal model averaging estimators of regression coefficients in a multinomial logit model,which is commonly used in many scientific fields.A Kullback-Leibler(KL)loss-based weight choice criterion is developed to determine averaging weights.Under some regularity conditions,we prove that the resulting model averaging estimators are asymptotically optimal.When the true model is one of the candidate models,the averaged estimators are consistent.Simulation studies suggest the superiority of the proposed method over commonly used model selection criterions,model averaging methods,as well as some other related methods in terms of the KL loss and mean squared forecast error.Finally,the website phishing data is used to illustrate the proposed method.展开更多
Based on a questionnaire data from 553 cities in China, this study used logistic regression to examine the effects of age, education, gender, occupation, and region on intercity talent mobility.The results revealed th...Based on a questionnaire data from 553 cities in China, this study used logistic regression to examine the effects of age, education, gender, occupation, and region on intercity talent mobility.The results revealed that individuals aged 26~45 years with work experience are more willing to relocate compared with most college students or individuals with little work experience. Furthermore,individuals who have acquired a bachelor’s degree are willing to relocate, whereas those who have acquired a master’s degree and above are less willing to relocate. In addition, cities offer a higher pay and better prospects for highly qualified individuals, so mobility seems less likely happen. Moreover,intercity mobility is higher for scientific research institutions than that for other industries. Talents tend to flow from central and western cities to eastern cities. Factors determining intercity talent mobility differ from region to region. Therefore, local governments, especially in central and western cities, should actively conduct research on talent strategies while promoting the construction of the city’s regional economy;formulate scientific policies on talent mobility;promote the reasonable flow of talent;and provide an effective talent pool for urban development.展开更多
为更全面研究高速公路车辆冲突风险的影响因素,笔者考虑微观与宏观因素影响,分析其可能存在的异质性,建立了随机参数Logit模型对其进行分析。使用高分辨率车辆轨迹数据,以碰撞时间(time to collision,TTC)为风险识别标准,提取风险发生前...为更全面研究高速公路车辆冲突风险的影响因素,笔者考虑微观与宏观因素影响,分析其可能存在的异质性,建立了随机参数Logit模型对其进行分析。使用高分辨率车辆轨迹数据,以碰撞时间(time to collision,TTC)为风险识别标准,提取风险发生前1 s内数据,处理得到车辆自身运动状态、与周围车辆的微观交互以及路段宏观交通流状态三类特征,并基于皮尔逊相关系数和嵌入法进行特征筛选;以筛选后的特征作为模型自变量,以车辆是否存在冲突风险为因变量,分别构建随机参数Logit模型以及考虑均值异质性的随机参数模型并进行对比。研究结果表明:考虑均值异质性的随机参数Logit模型拟合效果最好,且三类变量均对冲突风险有显著影响,其中车辆自身运动状态的波动以及车辆与前方车辆的速度差与风险呈正相关,相邻车道的大车比例与风险呈负相关;车辆自身运动状态以及与前方车辆的微观交互两类特征对冲突风险影响较大,而宏观交通特征的影响相对较小。展开更多
A growing stream of study stresses the relevance of subjective elements in understanding the hierarchy of preferences that underpin individual travel behavior. The purpose of this study is to evaluate the impact of va...A growing stream of study stresses the relevance of subjective elements in understanding the hierarchy of preferences that underpin individual travel behavior. The purpose of this study is to evaluate the impact of various factors on mode choice. To achieve this, a multinomial logit model (MNL) was used to analyze the relationships between mode choice and three classes of attributes;Combined Active and Latent, Active only and Latent only attributes. The data used are derived from surveys in the port city of Douala, Cameroon as a case study. Results stipulated that, the combined attributes model performed better than both active only attributes and latent only attributes models. Likewise, latent only attributes model performed better than active only attributes model. The advantage of modelling all three groups is for better selection of the most relevant attributes, and this is very relevant in understanding travel behavior of individuals and mode choice decisions.展开更多
文摘In this paper, we explore the properties of a positive-part Stein-like estimator which is a stochastically weighted convex combination of a fully correlated parameter model estimator and uncorrelated parameter model estimator in the Random Parameters Logit (RPL) model. The results of our Monte Carlo experiments show that the positive-part Stein-like estimator provides smaller MSE than the pretest estimator in the fully correlated RPL model. Both of them outperform the fully correlated RPL model estimator and provide more accurate information on the share of population putting a positive or negative value on the alternative attributes than the fully correlated RPL model estimates. The Monte Carlo mean estimates of direct elasticity with pretest and positive-part Stein-like estimators are closer to the true value and have smaller standard errors than those with fully correlated RPL model estimator.
基金Under the auspices of National Natural Science Foundation of China (No. 40801063, 70373029)Jiangsu Provincial Society Foundation (No. 06EYB004)
文摘Since land and labor force are primary resources to be used and controlled by rural households, the allocation of labor forces will influence land uses, and further lead to land use conversion. The present study used the Binary Logit model to investigate the influence of labor force transfer, characteristics of rural households, location, and land market on agricultural land use conversion at rural household level. This study was conducted based on 329 valid questionnaires, which were obtained in Changshu, Rudong, and Tongshan counties, respectively representing the southern, middle and northern areas of Jiangsu Province. The results showed that land market participation, location, zonal difference and labor transfer had strong influences on agricultural land use conversion. The participation of land market had a strong positive effect on land use conversion, especially for the farmland converted to the fishpond. The nearer to the county seat, the more conversion of land use occurred. Particularly, the labor force transfer caused by wage employment decreased this conversion probability, while the labor transfer caused by self-employment led to more conversion; and the increasing of income from labor transfer increased the conversion. Moreover, land use con- versions demonstrated zonal difference, which were more in Rudong and Changshu counties than in Tongshan County, and the factors influencing this conversion were different in the three regions.
文摘The need for travel demand models is growing worldwide. Obtaining reasonably accurate level of service (LOS) attributes of different travel modes such as travel time and cost representing the performance of transportation system is not a trivial task, especially in growing cities of developing countries. This study investigates the sensitivity of results of a travel mode choice model to different specifications of network-based LOS attributes using a mixed logit model. The study also looks at the possibilities of correcting some of the inaccuracies in network-based LOS attributes. Further, the study also explores the effects of different specifications of LOS data on implied values of time and aggregation forecasting. The findings indicate that the implied values of time are very sensitive to specification of data and model implying that utmost care must be taken if the purpose of the model is to estimate values of time. Models estimated on all specifications of LOS-data perform well in prediction, likely suggesting that the extra expense on developing a more detailed and accurate network models so as to derive more precise LOS attributes is unnecessary for impact analyses of some policies.
基金supported by Natural Science Foundation of China(No.11771268)a center named Shanghai Research Center for Data Science and Decision Technology.
文摘In this paper,we study optimal model averaging estimators of regression coefficients in a multinomial logit model,which is commonly used in many scientific fields.A Kullback-Leibler(KL)loss-based weight choice criterion is developed to determine averaging weights.Under some regularity conditions,we prove that the resulting model averaging estimators are asymptotically optimal.When the true model is one of the candidate models,the averaged estimators are consistent.Simulation studies suggest the superiority of the proposed method over commonly used model selection criterions,model averaging methods,as well as some other related methods in terms of the KL loss and mean squared forecast error.Finally,the website phishing data is used to illustrate the proposed method.
基金Supported by the Social Science Fund of Xinjiang (17BKS008)National Natural Science Foundation of China (71988101)。
文摘Based on a questionnaire data from 553 cities in China, this study used logistic regression to examine the effects of age, education, gender, occupation, and region on intercity talent mobility.The results revealed that individuals aged 26~45 years with work experience are more willing to relocate compared with most college students or individuals with little work experience. Furthermore,individuals who have acquired a bachelor’s degree are willing to relocate, whereas those who have acquired a master’s degree and above are less willing to relocate. In addition, cities offer a higher pay and better prospects for highly qualified individuals, so mobility seems less likely happen. Moreover,intercity mobility is higher for scientific research institutions than that for other industries. Talents tend to flow from central and western cities to eastern cities. Factors determining intercity talent mobility differ from region to region. Therefore, local governments, especially in central and western cities, should actively conduct research on talent strategies while promoting the construction of the city’s regional economy;formulate scientific policies on talent mobility;promote the reasonable flow of talent;and provide an effective talent pool for urban development.
文摘为更全面研究高速公路车辆冲突风险的影响因素,笔者考虑微观与宏观因素影响,分析其可能存在的异质性,建立了随机参数Logit模型对其进行分析。使用高分辨率车辆轨迹数据,以碰撞时间(time to collision,TTC)为风险识别标准,提取风险发生前1 s内数据,处理得到车辆自身运动状态、与周围车辆的微观交互以及路段宏观交通流状态三类特征,并基于皮尔逊相关系数和嵌入法进行特征筛选;以筛选后的特征作为模型自变量,以车辆是否存在冲突风险为因变量,分别构建随机参数Logit模型以及考虑均值异质性的随机参数模型并进行对比。研究结果表明:考虑均值异质性的随机参数Logit模型拟合效果最好,且三类变量均对冲突风险有显著影响,其中车辆自身运动状态的波动以及车辆与前方车辆的速度差与风险呈正相关,相邻车道的大车比例与风险呈负相关;车辆自身运动状态以及与前方车辆的微观交互两类特征对冲突风险影响较大,而宏观交通特征的影响相对较小。
文摘A growing stream of study stresses the relevance of subjective elements in understanding the hierarchy of preferences that underpin individual travel behavior. The purpose of this study is to evaluate the impact of various factors on mode choice. To achieve this, a multinomial logit model (MNL) was used to analyze the relationships between mode choice and three classes of attributes;Combined Active and Latent, Active only and Latent only attributes. The data used are derived from surveys in the port city of Douala, Cameroon as a case study. Results stipulated that, the combined attributes model performed better than both active only attributes and latent only attributes models. Likewise, latent only attributes model performed better than active only attributes model. The advantage of modelling all three groups is for better selection of the most relevant attributes, and this is very relevant in understanding travel behavior of individuals and mode choice decisions.
