Data preprocessing and quantile regression for probabilistic load forecasting in the GEFCom2017 final match

Team QUINKAN competed in the GEFCom2017 final match of hierarchical probabilistic load forecasting by adopting the quantile regression method using the R package quantreg. The weather stations were clustered into 11 groups, from which an optimal one was chosen for each load meter using the boosting method. The load meter records were cleaned and/or supplemented by various methods in order to secure robust quantile predictions. The variation in the regression formulas was kept as small as possible by introducing measures for suppressing prediction instability, although special formulas were employed for loading meters that were of an industrial nature. Several procedures were applied to help improve the accuracy, such as the smoothing of season transitions, coarse graining of the relative humidity, the use of load-oriented day-type definition, the averaging of weather data, and outlier removal.     

我国丘陵山区农机化水平影响因素及区划研究*——基于全国丘陵山区238个县（市）的调研数据

[目的]通过对全国丘陵山区县(市)与农机化有关的社会、经济和自然条件等因素进行调研所获取的238个有效样本进行分析,研究影响我国丘陵山区农机化水平的因素及其贡献,进而对我国丘陵山区进行区域划分。[方法]运用线性回归法对影响丘陵山区农机化水平的影响因素进行分析,进而对农机化水平产生显著影响的因素进行聚类分析。[结果]国内生产总值、农业劳动力数量对农机化水平产生极显著影响,耕地禀赋条件、务工工资、耕地规模、农机合作社数量和农机推广人员数量对农机化水平产生显著影响。对我国丘陵山区农机化水平呈正相关关系的因素有国内生产总值、务工工资、耕地规模、农机合作社数量,呈负相关的因素有耕地禀赋条件、农业劳动力数量、农机推广人员数量和农机化水平。[结论]我国可丘陵山区划分为中西、东南部地区,北部地区和东部沿海地区3大类地区。     

土地整治对中国粮食产出稳定性的贡献

研究目的:研究土地整治对粮食产出稳定性的贡献,为制定合理高效的土地整治政策,促进粮食增产稳产提供依据。研究方法:采用H-P滤波法实证分析中国粮食产量的波动性及增长趋势,然后基于C-D生产函数,分别建立趋势产量和波动强度面板回归模型,分析土地整治对粮食产出稳定性的影响。研究结果:(1)粮食作物播种面积、农业机械总动力、农用化肥施用量均对粮食长期趋势产生不同程度促进作用;农业劳动力对主产区粮食长期趋势影响显著为负,对非主产区却有正向影响。(2)土地整治面积和单位面积投资额均降低了全国及主产区粮食产量的波动程度,土地整治规模在全国和主产区的影响系数分别为-1.4162和-2.2215;单位土地整治面积投资额在全国和主产区的影响系数分别为-0.7589和-1.3509。(3)土地整治新增耕地面积对全国和主产区的粮食产量波动强度影响为正,影响系数分别为0.8018和1.3931。可能是通过土地整治新增的耕地质量较低,产出不高,导致了粮食产量波动。土地整治投入在非主产区均表现为不显著。研究结论:应继续推进尤其是主产区的土地整治项目实施,加大土地整治投资强度,建立长期稳定的投入机制,合理使用整治资金,注重提高新增耕地质量和综合生产能力,同时将土地整治投入和管理机制与农业生产系统运行机制、自然因素等有效结合,并制定差别化区域政策,以保障粮食增产稳产和区域协调发展。     

公司为什么放弃债务的收益呢？

经典资本结构理论认为债务具有税盾效应和财务杠杆效应，因此公司会选择适当的负债以获得债务的税收收益。但是，现实中一些公司的负债很低，甚至为零。公司为什么放弃债务的税收收益呢？本文以2007～2011年中国A股上市公司为研究样本，从行为公司金融的视角分析管理者能力是否导致公司采用“低杠杆”策略。结果表明，中国上市公司存在普遍的低杠杆现象，管理者能力的差异是导致公司采用“低杠杆”策略的重要原因。     

山东省耕地后备资源变化及驱动因素分析

[目的]揭示耕地后备资源变化规律及其驱动因素是进行耕地后备资源合理保护、开发利用的重要基础,但目前对于耕地后备资源变化及驱动因素的研究较为匮乏。[方法]文章以山东省为例,基于2003年和2015年两期耕地后备资源数据库,在分析耕地后备资源时空变化的基础上,采用空间回归模型分析了其变化的驱动因素。[结果]2003~2015年期间,山东省集中连片耕地后备资源减少了30.81万hm~2,其中可开垦土地减少24.97万hm~2,可复垦土地减少5.84万hm~2。[结论]总人口、文盲率、农民人均纯收入、建设用地扩张速度、第一产业产值占总产值比重等是山东省耕地后备资源变化的显著性驱动因素,并且总人口和建设用地扩张的驱动作用最大,受教育程度和产业结构调整的作用次之,农民人均纯收入变化对耕地后备资源变化的影响最小。"宏观统筹协调,异地代补"是解决"耕地后备资源空间分布不均衡、供需不匹配",实现耕地占补平衡、高效合理的开发利用耕地后备资源的必经之路。但异地代补的数量比例和质量应严格控制,并注重对补充耕地地区的经济补偿和政策倾斜,逐步缩小与发达地区之间的差距。     

Residents' place image: a cluster analysis and its links to place attachment and support for tourism

While there is a plethora of studies segmenting the lucrative tourism market, limited attention has been given to identifying potential segments of local residents based on their image of the place they live in as a tourist destination. This study aims to address this gap by (a) clustering local residents of a tourist destination based on their images of that place; and (b) identifying whether those image-based resident groups share similar/different levels of place attachment and intentions toward tourism (support for tourism, intention to recommend it to others). Analysis was based on a sample of 368 residents of Eilat, Israel. The findings suggest the presence of three resident groups with different images of Eilat – called Nature Aesthete, Appreciator, and Critical – and provide support that these groups exhibit dissimilar levels of attachment and intentions/behavior toward tourism. The Appreciator (residents with the most favorable image) were reported exhibiting higher levels of place attachment, support for tourism and were more likely to recommend their place to others as a tourist destination than the Critical (residents with the least favorable image). The implications of these findings to tourism theory and practice are discussed.     

Reconciling Alternative Theories for the Safety of Owner–Operators

Motor carrier safety is an important concern of shippers, carriers, policy makers, consignees, insurance providers, and the motoring public. One aspect of carrier safety that has garnered substantial attention is whether carriers making greater use of owner–operators are more or less safe vis‐à‐vis carriers making greater use of employee drivers. Currently, conflicting theoretical predictions exist regarding the direction of this relationship. In this article, we offer a reconciliation of the alternative theoretical predictions by developing a coherent theory that merges sociological rational choice theory and theory regarding motor carrier safety. We subject our theory to empirical testing by fitting a series of seemingly unrelated regression models to a vector of safety measures tracked as part of the Federal Motor Carrier Safety Administration's Compliance, Safety, and Accountability program. Our results are consistent with our proposed theory of owner—operator safety and provide meaningful theoretical and managerial implications and directions for future research.     

Effective HR implementation: the impact of supervisor support for policy use on employee perceptions and attitudes

Abstract

Effective implementation of human resource (HR) policies appears to depend on supervisors’ active involvement in the intervention process. Following recommendations of a recent intervention evaluation framework, we examine how perceived supervisor support during the implementation of a work-life intervention helps to change participants’ perceptions of organizational family supportiveness, and how this ultimately changes participants’ engagement and turnover intentions. A three-wave longitudinal study in a professional services firm (N = 434) that has formally involved supervisors in the process of a work-life intervention showed support for our study hypotheses. Supervisor support for policy use influenced employees’ positive work–home culture perceptions, which in turn strengthened employees’ work engagement and diminished their turnover intentions over time. We discuss practical implications and give recommendations on the future design of HR interventions and related policies.     

Gender wage gaps and economic crisis in Greece

ABSTRACT

We examine gender wage gap (GWG) in Greece for 2013, by using a survey data set. Our findings show first, that the unadjusted GWG is 15.3%, while European Commission reports a value of 15%. Secondly, we derive the ‘adjusted’ GWG, using the Oaxaca and Ransom (OR) and the Juhn, Murphy and Pierce (JMP) methods to be ranging from 10% to 13.6%. Thirdly, looking into the behaviour of the full population, we find a decreasing trend for the discrimination effects, an increasing trend for the residuals effects and a ‘random’ endowments effects while moving to higher deciles. These three effects are associated to the economic crisis 2008–2015. Fourthly, our findings do not show evidence of either a ‘glass ceiling’ effect or a ‘sticky floor’ effect. Finally, that there is strong evidence that investing in higher education reduces the wage discrimination between sexes.