手机App列表信息在信用风险评价中的应用——基于互联网借贷平台的实证研究

随着互联网的发展和智能手机的普及，用户手机数据被用来评估借款人的信用风险，使用到的数据有通讯记录、短信息接发、移动轨迹、用户行为数据等，而本文研究了手机上所安装的App列表和借款人信用风险之间的关系。通过对某大型互联网借贷平台上的个人借贷数据以及借款人手机上安装的App列表数据的分析发现，手机上安装的App和借款人的信用状况存在关联关系。安装生活类、金融类和买房买车类App的借款人比没有安装这些App的借款人信用风险低；其中，记账类App、外卖类App、股票类App和买房类App对借款人的信用风险有较强的识别能力。把手机App列表信息加入信用风险评价模型之后，信用风险评价模型的区分能力得到显著提高。     

A Reality Check for Data Snooping

Data snooping occurs when a given set of data is used more than once for purposes of inference or model selection. When such data reuse occurs, there is always the possibility that any satisfactory results obtained may simply be due to chance rather than to any merit inherent in the method yielding the results. This problem is practically unavoidable in the analysis of time‐series data, as typically only a single history measuring a given phenomenon of interest is available for analysis. It is widely acknowledged by empirical researchers that data snooping is a dangerous practice to be avoided, but in fact it is endemic. The main problem has been a lack of sufficiently simple practical methods capable of assessing the potential dangers of data snooping in a given situation. Our purpose here is to provide such methods by specifying a straightforward procedure for testing the null hypothesis that the best model encountered in a specification search has no predictive superiority over a given benchmark model. This permits data snooping to be undertaken with some degree of confidence that one will not mistake results that could have been generated by chance for genuinely good results.     

信息禀赋差异下制造商信息获取策略：“躺平”或“进取”

在市场需求信息不对称下，没有需求预测能力的制造商总是需要权衡实施“躺平”策略还是“进取”策略来获取下游零售商拥有的需求信息。本文考虑一个制造商和一个零售商组成的供应链，通过构建信息对称、信息推测和信息甄别三种情形下的博弈模型，分析了制造商的最优信息获取策略、不同策略和信息禀赋优势对制造商、零售商决策的影响。研究发现，无论零售商信息禀赋优势高或低，对于制造商来说，“躺平”策略为其最优信息获取策略，且在该策略下制造商更倾向于根据零售商的零售价对需求信息进行推测。而对于零售商来说，制造商选择“进取”策略时对其最有利。若制造商选择“躺平”策略，零售商则更倾向于主动披露信息，在该情形下零售商的信息禀赋优势越低对零售商越有利，越高则对制造商越有利。     

论英汉时空特质连续统及其对二语习得的启示——兼与王文斌教授商榷

不同学者对英汉时空特质提出了不同的见解。表面上看，是由于不同的研究视角引致，深层次剖析却发现是因为英汉时空特质自身是一个连续统所致。具体来看，英语在词语层面凸显出“时间性”特质，到词组、句子和语篇层面，空间性则逐渐加强，在多义句、语篇层面主要反映出空间性；汉语在词语层面凸显出“空间性”特质，到词组、句子和语篇层面，时间性则逐渐加强，在多义句、语篇层面主要反映出时间性。厘清英汉时空特质连续统有助于准确预见EFL学习者可能遇到的困难，选择学习的重难点，采取恰当的教学方法，最终提高二语习得实效。     

基于区间灰作用量的GM(1,1)均值差分模型解的非唯一性研究

GM(1,1)是结构信息不完全的灰色预测模型，但当前其模拟及预测结果的实数形式不满足灰色理论解的非唯一性原理。文章从GM(1,1)网络模型出发，分析了灰作用量的背景与内涵，还原了影响因素不确定条件下灰作用量的区间灰数形式，构建了具有非唯一解的新型GM(1,1)均值差分模型。新模型具有更加完善的体系结构，同时能实现对传统 GM(1,1)均值差分模型的完全兼容。应用新模型对我国电力能源消费量进行建模，结果显示其建模结果的合理性优于传统 GM(1,1)模型。本研究成果对丰富灰色预测模型理论框架、完善灰色预测模型结构体系具有积极意义。     

季节性数据特征驱动的电子废弃物回收规模分解集成预测建模研究

电子废弃物回收规模预测是政府制定循环经济发展规划和有关补贴政策、企业进行资源回收价值评估和产能优化的基础。本文考虑电子废弃物回收规模季度数据的季节性数据特征可能导致传统单模型预测误差偏大、预测结果不稳定等问题，基于“分解-集成”的思想提出了季节性数据特征驱动的电子废弃物回收规模预测CH-X12/STL-X框架。首先，基于Canova-Hansen(CH)检验对电子废弃物回收规模时间序列的季节性数据特征进行识别，继而对适于进行季节性分解的时间序列采用X12乘法模型或时间序列季节性分解(Seasonal-trend Decomposition Procedure Based on Loess，STL)模型实现季节性分量提取。然后，采用Holt-Winters模型对获得的季节性分量进行预测，并以支持向量回归模型(Support Vector Regression，SVR)预测分解获得的其他分量。最后，通过对各个分量预测结果的线性求和以得到最终的预测结果。实证结果表明，提出CH-X12/STL-X预测框架能够较好地满足不同季节性数据特征驱动的时间序列预测建模需求，且较传统单模型(Holt-Winters模型、季节性差分自回归滑动平均模型、SVR模型)在预测性能上表现良好且稳定。     

Quantitative risk assessment-epidemic curve prediction model for leafy green outbreak investigation

The objective of this study was to leverage quantitative risk assessment to investigate possible root cause(s) of foodborne illness outbreaks related to Shiga toxin-producing Escherichia coli O157:H7 (STEC O157) infections in leafy greens in the United States. To this end, we developed the FDA leafy green quantitative risk assessment epidemic curve prediction model (FDA-LG QRA-EC) that simulated the lettuce supply chain. The model was used to predict the number of reported illnesses and the epidemic curve associated with lettuce contaminated with STEC O157 for a wide range of scenarios representing various contamination conditions and facility processing/sanitation practices. Model predictions were generated for fresh-cut and whole lettuce, quantifying the differing impacts of facility processing and home preparation on predicted illnesses. Our model revealed that the timespan (i.e., number of days with at least one reported illness) and the peak (i.e., day with the most predicted number of reported illnesses) of the epidemic curve of a STEC O157-lettuce outbreak were not strongly influenced by facility processing/sanitation practices and were indications of contamination pattern among incoming lettuce batches received by the facility or distribution center. Through comparisons with observed number of illnesses from recent STEC O157-lettuce outbreaks, the model identified contamination conditions on incoming lettuce heads that could result in an outbreak of similar size, which can be used to narrow down potential root cause hypotheses.     

基于滚动时间窗的碳市场价格分解集成预测研究

提高碳市场价格预测准确性对于交易风险监测以及碳市场平稳发展具有重要价值。针对复杂的、非线性碳市场价格数据的短期预测误差偏大、分解过程易产生数据泄露问题，提出了基于滚动时间窗的SSA-SVR分解集成预测框架。首先，选取时间窗数据，继而借助奇异谱分析将时间窗内碳价序列分解重构为高、低频序列；然后，使用支持向量回归方法对高、低频序列分别进行预测；最后，加和集成预测结果，得到下一时刻的碳市场价格预测值。通过不断更新时间窗的数据内容，动态执行“分解-预测-集成”过程，实现碳市场价格的实时预测。研究结果表明，本文所提出框架表现出优异且稳定的预测性能，在碳市场价格预测研究中具有良好的适用性和有效性。     

A model-averaging treatment of multiple instruments in Poisson models with errors

We analyze Poisson regression when covariates contain measurement errors and when multiple potential instrumental variables are available. Without empirical knowledge to select the most suitable variable as an instrument, we propose a novel model-averaging approach to resolve this issue. We prescribe an implementation and establish its optimality in terms of minimizing prediction risk. We further show that, as long as one model is correctly specified among all potential instrumental variable models, our method will lead to consistent prediction. The performance of our method is illustrated through simulations and a movie sales example.