UNCERTAINTY OF EXTREME FLOOD ESTIMATES INCORPRATING HISTORICAL DATA1

ABSTRACT: The ability to predict extreme floods is an important part of the planning process for any water project for which failure will be very costly. The length of a gage record available for use in estimating extreme flows is generally much shorter than the recurrence interval of the desired flows, resulting in estimates having a high degree of uncertainty. Maximum likelihood estimators of the parameters of the three parameter lognormal (3PLN) distribution, which make use of historical data, are presented. A Monte Carlo study of extreme flows estimated from samples drawn from three hypothetical 3PLN populations showed that inclusion of historical flows with the gage record reduced the bias and variance of extreme flow estimates. Asymptotic theory approximations of parameter variances and covariances calculated using the second and mixed partial derivatives of the log likelihood function agreed well with Monte Carlo results. First order approximations of the standard deviations of the extreme flow estimates did not agree with the Monte Carlo results. An alternative method for calculating those standard deviations, the “asymptotic simulation” method, is described. The standard deviations calculated by asymptotic simulation agree well with the Monte Carlo results.     

Observer reactions to interpersonal injustice: The roles of perpetrator intent and victim perception

The present research contributes to a growing literature on observer reactions to injustice experienced by others. In particular, we separated two variables that have previously been confounded in prior research, namely perpetrator intent to cause harm and victim perception of harm. We expected that injustice intent and injustice perceptions would have both unique and joint effects on observer reactions. The results of three experiments in which we manipulated perpetrator injustice intent and victim injustice perceptions supported our predictions. First, we found that observers had more negative reactions toward superiors who intended to inflict high versus low levels of interpersonal injustice toward a subordinate. Second, the injustice intent of the superior influenced observers' reactions more than did victim perceptions of injustice. Third, most novel, we found that the mere intent to cause injustice generated negative reactions in observers, even in the absence of a “true” victim—that is, when the subordinate perceptions of injustice were low. Together, our results emphasize the importance of examining observers' reactions to injustice and incorporating perpetrator intentions into the study of organizational justice. Copyright © 2012 John Wiley & Sons, Ltd.     

基于情绪分析的事故风险感知偏差研究*

为探索公众对安全事故的风险感知,运用文本挖掘技术获得事故微博评论数据,采用中文风险感知双向编码转换器(BERT-RPC)识别惊讶和恐惧情绪,以频率惊讶测量事故概率感知偏差,以恐惧和损失惊讶测量事故损失感知偏差,基于二元逻辑回归考察微博形式和内容对风险感知的影响。结果表明:低估安全事故风险的现象普遍存在,且对事故损失的低估更为突出;基于BERT-RPC模型的\"抓取-分析\"技术能够高效、低延迟地实现全网公众的风险感知偏差监测;交通行业的事故概率、损失被严重低估;一般事故的概率和特大事故的损失被严重低估;事故图片和视频有助于纠正事故损失的感知偏差,但对概率感知偏差作用有限;事故爆发初期报道对公众风险感知纠正效果最佳,调查结果公布和责任人宣判阶段次之。     

Constituency Bias in a Federal Resource Management Agency: a Confirmatory Analysis

In a 1989 article, Ben Twight and Fremont Lyden compared the attitudes of national forest managers in the United States in 1981 with those of its major constituents to assess the extent to which the U.S. Forest Service was biased: were the beliefs and values of agency employees concerning resource management more representative of one of two major constituent groups, environmentalists and forest utilizers? The research tested Culhane's (Public Lands Politics: Interest Group Influence on the Forest Service and the Bureau of Land Management. Baltimore, Maryland: John Hopkins University Press. 1981) theory that the Forest Service occupies a middle ground in its attitudes relative to those of its environmental and utilization constituencies. They concluded that the agency did not; ideologically, district rangers were quite close to the Forest Service's utilizer constituency and relatively far from its environmentalist constituency. Given recent changes in the attitudes of Forest Services managers, the present study sought to answer the question: what do these changes reveal about the ideological position of the agency in 1981 vis a vis its position in 1990, and what are their implications for continuing concerns over the agency's representation of all interest groups? The response to survey questions of four groups—1990 district rangers and district rangers, environmentalists and forest utilizers in 1981—were combined for statistical comparison. Discriminant analyses were conducted to clarify the differences in the groups. Although the hypothesized bias of the Forest Service toward the traditional utilizer position was confirmed, the results also suggested that managers' values and attitudes had changed over the decade. The major issue underlying this bias—preservation versus utilization of resources—no longer adequately represented the agency's position, which has been fragmented into concerns with multiple issues.     

固相萃取-高效液相色谱法测定水中微囊藻毒素质量控制指标研究

采用固相萃取－液相色谱法,通过统计全国多家实验室的测定数据,对水中微囊藻毒素测试的平行样测定相对偏差、空白加标回收率、实际样品加标回收率、空白加标回收率平行样相对偏差以及样品加标回收率平行样相对偏差5个质控指标进行了研究,并给出了质控指标评价标准,提出在概率P和γ均为0.90时,其平行样测定允许最大相对偏差应控制在7.3%;空白加标质量浓度为0.005~20 μg/L时,回收率的控制范围为61%~125%;样品测定浓度为未检出、加标质量浓度在0.2~3.6 μg/L时,实际样品加标回收率控制范围为66%~108%;空白加标、样品加标回收率平行样最大相对偏差应分别控制在3.9%和8.9%。在概率P和γ均为0.95时,其平行样测定允许最大相对偏差应控制在8.3%;空白加标质量浓度为0.005~20 μg/L时,回收率的控制范围为49%~137%;样品测定浓度为未检出、加标质量浓度在0.2~3.6 μg/L时,实际样品加标回收率控制范围为60%~114%;空白加标、样品加标回收率平行样最大相对偏差应分别控制在5.2% 和14.8%。     

A reporting guide for studies on individual differences in traffic safety

Problem

Studies on individual differences in traffic safety report differently on their methodologies, and use different statistics, and these are therefore difficult to compare and meta-analyze.

Method

Based upon a previous, extensive review and meta-analysis of the traffic safety literature, several recommendations are made about what features of the methodology of studies on individual differences (including evaluations) in safety need to be reported to facilitate interpretation and meta-analysis. Similarly, some basic types of statistical values are recommended.

Impact on Industry

The accumulation of knowledge about individual differences in traffic safety would be facilitated if scientific authors and journals adhered to these guidelines.     

EFFECT OF SERIAL CORRECTION ON GROUND WATER QUALITY SAMPLING FREQUENCY1

ABSTRACT: Methods of calculating uncertainty in estimates of serial correlation coefficients, and correcting for bias in short and medium length (less than 50 data point) records, are presented. Uncertainty and bias in the estimation of serial correlation coefficients for ground water quality data is shown to be considerable and to result in inaccurate calculation of the sampling frequencies for monitoring purposes. The methods are applied to a ground water data set consisting of 87 monthly measurements of nitrate concentrations. The variation in serial correlation coefficients with variation of record length is examined. The optimum sampling frequencies for detection of changes in ground water nitrate concentrations are estimated.