Logit modeling for classification of monocultivar olive oils from southwest Spain: A preliminary study

A characterization study of the main olive oil cultivars of southwest Spain (Picual, Arbequina, and Verdial) has been performed in order to establish logistic regression models. Several quality characteristics (free acidity, peroxide value, K₂₃₂, K₂₇₀, oxidative stability index) and chemical data (fatty acids, sterols, erythrodiol–uvaol composition) were measured. Logit regressions were used to evaluate the correlation of the parameters and to create models that allow saving costs on identifying oils as Arbequina, Picual, or Verdial type. Multiple logit regression models were developed: one for Arbequina, three models for Picual, and two models for Verdial cultivar, allowing in this way to minimize the cost for classifying oil samples. Practical application: The olive oil marketing is increasingly focused on the chemical differentiation and characterization of the product because the chemical composition of these virgin oils is responsible for their valuable sensory and nutritional properties. Here we present a characterization study (quality characteristics and chemical data) from the main olive oil cultivars of southwest Spain, Picual, Arbequina, and Verdial, as a first step for the traceability of these three types of monocultivar virgin olive oils. The results may be used as a training to create models for other olive oil cultivars.     

Logit模型下的道路拥堵收费策略改善效果分析

为探讨拥堵收费策略的改善效果,从出行者的综合成本出发,构建适用于拥堵收费的路阻函数和Logit交通分配模型,探讨拥堵收费下交通出行在路网上的重新分配.并以南京市应天大街高架为例设置了拥堵收费虚拟方案,应用路阻函数和交通分配模型进行分析后得出拥堵收费在交通出行量分布、出行分担率、道路服务水平和行程速度上的改善效果.结果表明:拥堵收费能有效引导交通出行的重新分布,提高路网总体通行效率和服务水平,可以认为拥堵收费对交通的改善具有一定效果,但改善效果和拥堵收费费率不是线性正比关系,本次虚拟收费方案下收费费率为5元/次时可取得最佳改善效果.     

Willingness-to-pay for reducing fatal accident risk in urban areas: an Internet-based Web page stated preference survey

Contemporary transport project evaluation requires the ability to value reductions in the number of estimated fatal and non-fatal accidents after project implementation. In this quest, we designed a stated preference (SP) experiment to estimate willingness-to-pay (WTP) for reducing fatal accident risk in urban areas. The survey was implemented in a Web page allowing rapid turnover and a complete customisation of the interview. The sample was presented with a series of route choice situations based on travel time, cost and number of car fatal accidents per year. With this data we estimated Multinomial Logit (MNL) and Mixed Logit (ML) models based on a consistent microeconomic framework; the former with linear and non-linear utility specifications and allowing for various stratifications of the data. The more flexible ML models also allow to treat the repeated observations problem common to SP data and, as expected, gave a better fit to the data in all cases. Based on these models, we estimated subjective values of time, that were consistent with previous values obtained in the country, and also sensible values for the WTP for reductions in fatal accident risk. Thus, the Internet appears as a potentially very interesting medium to carry out complex stated choice surveys.     

基于一种新效用函数形式的分层Logit模型

令效用函数为代表性效用和随机项的乘积,给出了对应的分层Logit模型的具体表达式。进一步地,令效用函数是两者的和积混合,即代表性效用分解为两部分之和,随机项分解为两部分之积,两者相乘构成选择项的效用函数,推导出选择某方案的边际概率和相应的条件概率,从而大大拓展了分层Logit模型的类型和应用范围。     

客运专线修建后城际旅客出行方式选择的变化

在分析影响旅客出行方式选择行为因素的基础上,根据Logit模型,选择经济性、快速性、方便性、舒适度、安全性为5个衡量指标并建立其广义费用函数,推导出客运专线修建前后城际旅客对各出行方式选择变化的计算模型,利用相关研究结果和极大似然估计法,确定模型参数。最后以郑西客运专线为例进行了模拟计算。结果表明,客运专线的技术经济特征决定了其能够给城际旅客带来较高的效用,客运专线修建后,选择铁路出行的城际旅客比例将大大提高。     

交通方式预测中Logit模型参数估计方法的应用研究

使用Logistic回归分析研究交通规划,并从理论和实际应用两个方面讨论了Logistic回归分析及其参数的标定方法,给出了集结模式下的交通方式预测的简便易行的解决方法;按照Logistic回归分析的思想,对未来丹东市居民出行方式进行了预测,计算结果与调查得到的出行方式比例十分吻合。结果表明:利用Logistic回归推测未来交通方式更为符合实际。     

离散选择模型的比较及其在零售业的应用

离散选择模型可以根据消费者的数据来分析其购买行为,进而为企业营销策略进行决策支持.本文解决了在动态客户关系管理中如何选择合适的离散选择模型这一问题.首先对Logit和Probit模型进行比较研究,其次确定消费者离散选择模型的评价指标,最后在零售业中使用消费者数据对评价指标进行验证.结果表明,所确定的消费者离散选择模型的评价指标可以用来进行模型的选择,Probit模型比Logit模型更适合于零售业的动态客户关系管理问题.同时本文的分析过程也为研究者和企业更好地理解和定量分析消费者购买行为提供了理论参考.     

农村信用社农户贷款的信用风险评价研究

根据实地调查资料,本文采用logit模型对我国农村农户贷款违约的影响因素进行了实证分析,结果表明:贷款利率、贷款期限、信用社服务、非种养业收入和自营支出对农户是否违约有着显著的影响;年龄、教育年限、农业支出对农户是否违约也有较大影响.     

Determinants of farmers’ decision to adopt or not adopt inorganic fertilizer in the savannas of northern Nigeria

Soil nutrient deficiency has hampered increased agricultural production in the savannas of northern Nigeria. It has been observed that inorganic fertilizer (IF) has the potential to reverse the situation. However, low adoption among the farmers has characterized IF in the savannas of northern Nigeria. The application rates have also fallen far lower than the rate recommended by research and extension, resulting in low crop yields. This paper investigates the factors that influence farmers' decision to adopt or not to adopt IF and to evaluate the elasticity of adoption. This information will help to prioritize the factors that affect IF adoption decisions and suggest pathways for effective promotion of IF. About 49% of the survey farmers adopted IF and the application rate ranges from 5.6 to 64.4 kg ha^–1 (with a mean of 24.1 kg ha^–1). The probability of adoption increases with increased targeting of: farmers from the Guinea savanna agroecological zone, younger farmers, better educated farmers, food secure farmers and net sellers of food grains, farmers who have diversified into many crops, farmers who perceive increase in the fertilizer needs of their crops, and farmers who apply large quantities of organic manure. Among others, the estimates of elasticity of adoption indicate that a 1% increase in the number of farmers who perceive an increase in the fertilizer needs of their crops results in 3.23% increase in the probability of IF adoption. The paper concludes with policy implications for strategies aimed at promoting IF in the savannas of Nigeria and similar ecologies elsewhere.     

基于Logit模型的农村灾后应急运输方式选择模型

基于多项Logit模型的基本理论构建了农村灾后应急运输方式选择模型,运用SAS数理统计软件对数据进行了多元线性回归处理,得到了多项Logit模型参数估计值,在建立运输方式选择模型的基础上,构造了求解该问题的虚拟运输网络,并进行了算例计算与分析,结果表明,应用多项Logit概率模型进行农村灾害应急物流运输方式选择是合理有效的。