Analysis of Covariance with Non-normal Errors

Analysis of covariance techniques have been developed primarily for normally distributed errors. We give solutions when the errors have non-normal distributions. We show that our solutions are efficient and robust. We provide a real-life example.     

Consumer willingness to pay for sustainable apparel: the influence of labelling for fibre origin and production methods

This study of value‐based labelling for apparel products examined consumer willingness to pay (WTP) for three credence attributes of fibre: origin, type and production method. Experimental auctions were conducted with student subjects in Texas and used socks made from cotton and polylactic acid (PLA), a fibre manufactured from corn. The bid results of two rounds were compared. The first round was conducted without information about the credence attributes of the socks. The second round included varying levels of three types of attributes: fibre origin (imported, US and Texas), fibre type (cotton and corn) and production method [conventional, organic and non‐genetically modified (GM)]. Tobit regression analysis was performed using the attributes and subject demographics to determine consumer WTP for the various attribute levels and to profile consumers with interest in the attributes. In terms of origin, results show that participants were willing to pay a premium for socks with fibres produced in Texas, but not for those produced in the US. Fibre type mattered, with participants requiring a discount once they learned that socks were made with PLA fibre. The greatest premium ($1.86) was placed on socks labelled as organic, slightly more than the premium for socks labelled as non‐GM. The results also indicate that women were less willing to pay for US fibres than men, and Hispanics were less willing to pay for organic or non‐GM fibre production. A key finding of this study is that consumers value information about the local origin of fibres. The premium for organic fibres is not unexpected, given the success of the organic apparel market, but the premium on non‐GM fibres suggests that sustainable production systems that are not organic may be successful if they emphasize other attributes such as local or non‐GM.     

Consumer attitudes toward genetically modified food in the United States: Are Millennials different?

ABSTRACT

Our study adds to the extant literature by focusing on Millennials, exploring possible generational shift that may have taken place in attitudes related to and consumption of such products. Results suggest that Millennials respond similarly as non-Millennials across several factors that shape consumers’ views and behaviors toward genetically modified technology and products. Millennials who are more educated and knowledgeable about biotechnology, though, are more willing to purchase GM foods. They perceive less risk and have fewer safety concerns compared to non-Millennials. Furthermore, male Millennials are more willing to purchase GM products and are more supportive of encouraging GM technology compared to female Millennials.     

Factors influencing adoption of genetically modified crops in Africa

The debate around genetically modified (GM) crops in Africa continues to grow especially among policy-makers, food manufacturers, farmer organisation and consumer advocacy groups and the general public. While other regions have taken a firm position on biotech crops, Africa remains largely ambivalent, with wide variation in GM policy across countries. The central objective of this paper is to analyse the factors that influence the adoption of GM crops in Africa. First we evaluate the current status of GM crop adoption in Africa. Second we identify the key enablers and hindrances to adoption of GM crops. The main factors include ministerial control of biosafety, peer country influence, stage of seed sector development, advocacy by key political figures, the media, activism, food security and technical capacity. We posit that, for most African countries, GM policy is guided by political rather than technological considerations with media and special interest groups playing a key role. Despite the numerous impediments, slow progress is being made in preparing the requisite enabling environment for biotechnology adoption in Africa.     

转基因食品引发的系统信任弱化及个体行动选择——基于上海市居民的调查研究

通过对上海市388份问卷调查及23个个案的访谈发现,在转基因食品风险下,公众对政府、专家的信任程度正在弱化;政府部门、专家学者和转基因厂商间的利益关涉,针对转基因食品专家系统内部的观点分歧,政府和专家系统决策过程的封闭性是引起系统信任弱化的主要因素。在系统信任弱化的情境下,公众采取了"自主决策"且"依赖传统"的双重行动策略:在自我决策、自主判断的基础上,公众期望通过选择传统天然食品来规避转基因食品蕴含的不确定性风险。要强化系统信任,应该加强对政府、专家的监督,提高公众的科学素养,建构开放性的政府及专家系统。     

修正损失率的溃坝洪水经济损失评估方法研究

为提高溃坝洪水经济损失评估的精度,研究分析了已有的溃坝洪水经济损失评估方法,提出运用损失率模型评估溃坝洪水经济损失时,应考虑溃坝洪水的特性,对损失率进行必要修正。除了考虑淹没水深和历时因素外,还定量地分析了溃坝洪水流速和预警时间对损失率的影响,对溃坝洪水进行影响分区,通过建立流速修正系数以及预警时间修正系数对损失率进行修正,并以刘家台水库为例进行了实例论证。结果表明,采用损失率修正模型可以更准确地评估溃坝洪水造成的经济损失。     

Risk Perceptions, Risk Preference, and Acceptance of Risky Food

Consumers' risk preferences are often overlooked in studies of consumer demand for risky food. We find that risk preferences elicited through context-less lottery choices are significantly related to consumers' stated preferences for genetically modified (GM) food. These results suggest risk preferences elicited in the laboratory are not artificial in the sense that they appear to be related to the same risk preferences that govern other individual decisions such as food choice. Consistent with theoretical expectations, risk perceptions and risk preferences were found to be significant determinants of acceptance of GM food, which has important implications for explaining consumer behavior.     

RTC路径下粉质粘土平面应变三轴试验研究及剑桥模型的修正

岩土类材料宏观力学特性有强烈的应力路径依赖性,不同应力路径下材料所表现出的应力应变特性存在较大的差异。对于实际工程中存在的卸荷路径工况,目前通常的做法是通过加载的试验方法确定岩土体力学参数和本构模型,这对于实际工程中的卸载路径工况可能会存在较大误差。因此,从实际下程出发,针对深基坑开挖时典型的侧向卸荷工况进行分析。利用多路径平面应变三轴仪对黄石青龙山麓粉质粘土进行了常规路径下平面应变三轴固结排水剪切试验（CTC路径）和减围压平面应变固结排水剪切试验（RTC路径）,对比分析2种应力路径下的试验现象,描述了二者的差异性,重点分析了RTC路径下试样所表现出来的力学特性。基于剑桥模型框架的前提下,推导出了基于本文材料的修正剑桥模型方程,为数值分析奠定了基础。     

修正后的KMV模型对我国上市公司信用风险度量的适用性分析

信用风险已成为当今金融市场的重要风险之一。本文试图通过修正KMV模型使之更适用于我国上市公司信用风险度量。通过实证研究对其结果加以分析表明,修正后的KMV模型由于数据采集相对容易,计算操作简便,比较适合目前我国的信用风险管理水平,可用于对我国上市公司信用风险的度量,在我国信用风险管理领域有着广阔的发展空间。     

A latent class approach to investigating demand for genetically modified banana in Uganda

This study explores consumer acceptance and valuation of a genetically modified (GM) staple food crop in a developing country prior to its commercialization. We focus on the hypothetical introduction of a disease‐resistant GM banana variety in Uganda, where bananas are among the most important staple crops. A choice experiment is used to investigate consumer preferences for various attributes related to the banana (such as bunch size, technology, producer benefit, and price) and examine their opinions on GM foodstuff. Choice data come from 421 banana‐consuming households randomly selected from three regions of Uganda. A latent class model is used to investigate the heterogeneity in consumers’ preferences for selected attributes related to the banana and to profile consumers who are more or less likely to accept GM bananas. Our results reveal that there is significant heterogeneity in consumer preferences across our sample. GM bananas are valued the most by poorer households located in the rural areas of the Eastern region. These food‐insecure households would experience the highest benefits (i.e., welfare gains) from the commercial release of GM bananas. In contrast, urban consumers are less accepting of GM bananas, and they would experience significant welfare losses if GM banana is released. According to our welfare estimates, both the total welfare benefits acquired by the gainers and the total welfare losses borne by the losers of this technology are significant and large. These results suggest the need for further investigation of the overall welfare effects of the introduction of GM bananas on the Ugandan society as a whole.