ON THE INDEPENDENCE OF THE SAMPLE MEAN AND TRANSLATION-INVARIANT STATISTICS FOR MATRIX NORMAL DISTRIBUTIONS

We present an explicit characterization of the joint dependency structure of an n×p matrix normal random matrix such that the p-dimensional sample mean vector is independent of all translation invariant statistics.     

Uncertain Numbers and Uncertainty in the Selection of Input Distributions—Consequences for a Probabilistic Risk Assessment of Contaminated Land

Risks from exposure to contaminated land are often assessed with the aid of mathematical models. The current probabilistic approach is a considerable improvement on previous deterministic risk assessment practices, in that it attempts to characterize uncertainty and variability. However, some inputs continue to be assigned as precise numbers, while others are characterized as precise probability distributions. Such precision is hard to justify, and we show in this article how rounding errors and distribution assumptions can affect an exposure assessment. The outcome of traditional deterministic point estimates and Monte Carlo simulations were compared to probability bounds analyses. Assigning all scalars as imprecise numbers (intervals prescribed by significant digits) added uncertainty to the deterministic point estimate of about one order of magnitude. Similarly, representing probability distributions as probability boxes added several orders of magnitude to the uncertainty of the probabilistic estimate. This indicates that the size of the uncertainty in such assessments is actually much greater than currently reported. The article suggests that full disclosure of the uncertainty may facilitate decision making in opening up a negotiation window. In the risk analysis process, it is also an ethical obligation to clarify the boundary between the scientific and social domains.     

Power and perceptions in participatory monitoring and evaluation

This paper examines the assumptions that commonly underpin the design of participatory monitoring and evaluation (PM&E) within development programmes through the examination of a case study of a large rural development programme in Uganda. This case study reveals a mismatch between programme assumptions and participant perceptions, which stymied the implementation of PM&E. In this case, PM&E was based on the assumptions that programme and participant goals were compatible, participants were willing to volunteer and engage themselves for the greater good of their communities, and information sharing and communication was fairly free and open. However, farmers within the programme felt that the bureaucratic and accountability requirements of the programme were not their concern, and were acutely aware of power differences between farmers and programme officials, and between farmers of varying status. The key lesson to be drawn from this case is the need for a heightened awareness of power dynamics and political factors in the design of PM&E.     

寡头企业价格领先竞争的均衡性

首先介绍完全信息时双寡头垄断的企业价格决策的静态模型,得到伯川德均衡;然后介绍完全信息时双寡头垄断的企业价格决策的动态模型,得到价格领先的寡头竞争模型均衡解;最后分析了后者的局限性,得到在理性假设的前提下价格领先的寡头竞争模型的均衡解不是一个稳定状态,完全信息时双寡头价格决策的动态博弈的结果必然最终趋近于静态博弈的结果。     

Final report of the Color Additive Scientific Review Panel

The Color Additives Scientific Review Panel considered whether there was information sufficient to perform a carcinogenic risk assessment on the colors D&C Red No. 19 (R-19), D&C Red No. 37 (R-37), D&C Orange No. 17 (O-17), D&C Red No. 9 (R-9), D&C Red No. 8 (R-8) and FD&C Red No. 3 (R-3) and to evaluate the assessments sent to FDA as part of the petitions for use of the colors for drug and external uses by the Cosmetic, Toiletry and Fragrance Association (CTFA). There is a lack of human data concerning the colors for making a human health assessment, so the assessments are based upon the extrapolation of animal data. The risk assessments are determined for exposure to single chemicals. Excluded from consideration are possible effects from exposure to multiple chemicals, such as co-carcinogenesis, promotion, synergism, antagonism, etc. In the light of recent efforts in establishing a consensus in risk assessment, the Panel has determined that the CTFA assessments for R-10, O-17, and R-9 are consistent with present acceptable usages, although it questions some of the assumptions used in the assessments. The Panel identified a number of general assumptions made, and discusses their validity, their impact on total uncertainty, and the potential options to address the gaps in understanding that necessitate the assumption. The Panel also derived revised risk estimates using more "reasonable" assumptions than "worst-case" situations, for 90th percentile and average exposure. For those assumptions that are easily quantifiable, the Panel's estimates are less than an order of magnitude lower than the CTFA risk estimates, indicating that the underestimates and overestimates of the CTFA risk estimates tend to balance each other. The impact of most of the assumptions is not quantifiable. The assessment for R-3 is complicated by the fact that there is no good skin penetrance study for this color. It was assumed that the penetrance is similar to that of another water-soluble xanthene color, R-19. It is expected that the absorption of the color is not likely to exceed that of the smaller molecule, R-19. Therefore, the risk estimates are similar to the CTFA estimates, but with different reasoning. The estimates for R-8 and R-37 are different from the others in that there is a lack of any exposure or toxicological information on these colors.(ABSTRACT TRUNCATED AT 400 WORDS)     

Conducting research using web-based questionnaires: Practical,methodological, and ethical considerations

The use of the internet for social science research is becoming increasingly common. This paper outlines practical, methodological and ethical issues for researchers to consider when using web-based questionnaires. This is illustrated by consideration of the authors' own experience of conducting a study into the phenomenon of self-harm.     

西方传统管理思想中的实体人性论

西方传统管理思想以实体人性论为哲学基础,用片面的、既定的、抽象的思维方式看待人。其各种人性假设从不同的角度抽象出人性的各种形态,阐述人的各种基本特性。由此他们提出各种不同甚至对立的管理理论,最终使得西方传统管理思想及其理论陷入困境而不能自拔。