Sample Size Determination for Categorical Responses

Abstract:  Procedures are reviewed and recommendations made for the choice of the size of a sample to estimate the characteristics (sometimes known as parameters) of a population consisting of discrete items which may belong to one and only one of a number of categories with examples drawn from forensic science. Four sampling procedures are described for binary responses, where the number of possible categories is only two, e.g., licit or illicit pills. One is based on priors informed from historical data. The other three are sequential. The first of these is a sequential probability ratio test with a stopping rule derived by controlling the probabilities of type 1 and type 2 errors. The second is a sequential variation of a procedure based on the predictive distribution of the data yet to be inspected and the distribution of the data that have been inspected, with a stopping rule determined by a prespecified threshold on the probability of a wrong decision. The third is a two-sided sequential criterion which stops sampling when one of two competitive hypotheses has a probability of being accepted which is larger than another prespecified threshold. The fifth procedure extends the ideas developed for binary responses to multinomial responses where the number of possible categories (e.g., types of drug or types of glass) may be more than two. The procedure is sequential and recommends stopping when the joint probability interval or ellipsoid for the estimates of the proportions is less than a given threshold in size. For trinomial data this last procedure is illustrated with a ternary diagram with an ellipse formed around the sample proportions. There is a straightforward generalization of this approach to multinomial populations with more than three categories. A conclusion provides recommendations for sampling procedures in various contexts.     

探讨服务型政府之法制构建

随着服务型政府这一概念的提出，有关构建服务型政府的研究与探索亦成为炙手可热的话题。但如果把构建服务型政府这一命题与建设社会主义法治国家相联系，则可以将服务型政府的法治内涵作为切入点，从立法、执法、司法的层面探讨其法制构建应着力避免的误区。     

Uncertainty in probabilistic genotyping of low template DNA: A case study comparing STRMix™ and TrueAllele™

Two probabilistic genotyping (PG) programs, STRMix™ and TrueAllele™, were used to assess the strength of the same item of DNA evidence in a federal criminal case, with strikingly different results. For STRMix, the reported likelihood ratio in favor of the non-contributor hypothesis was 24; for TrueAllele it ranged from 1.2 million to 16.7 million, depending on the reference population. This case report seeks to explain why the two programs produced different results and to consider what the difference tells us about the reliability and trustworthiness of these programs. It uses a locus-by-locus breakdown to trace the differing results to subtle differences in modeling parameters and methods, analytic thresholds, and mixture ratios, as well as TrueAllele's use of an ad hoc procedure for assigning LRs at some loci. These findings illustrate the extent to which PG analysis rests on a lattice of contestable assumptions, highlighting the importance of rigorous validation of PG programs using known-source test samples that closely replicate the characteristics of evidentiary samples. The article also points out misleading aspects of the way STRMix and TrueAllele results are routinely presented in reports and testimony and calls for clarification of forensic reporting standards to address those problems.     

浅谈网络舆论对侦查询问的影响

刑事案件发生后,网络上充斥着大量有关该案的信息,侦查人员接触这些信息,会形成偏见,以至在侦查询问中提出带有暗示性和倾向性的问题;而记忆是可塑的,信息误导效应会利用记忆的可塑性在证人不自知的情况下,改变其记忆;网络舆论的倾向性,也会影响证人的情绪和立场,影响证人的作证动机。     

The Name of the Rose

Party names have been collected since ‘Whig’ and ‘Tory’ meant ‘Scotch rebel’ and ‘Irish bandit’. ‘Conservative’ began as a catch‐all on the right when one did not use the word ‘right’ in politics, struggled with ‘Unionist’ until Ireland got away and was a euphemism for ‘Tory’ before the Americans used it to describe howling extremists. ‘Labour’ meant skilled men in best suits and school teachers with elbow patches, and now has the resonance of Nineveh and Tyre.     

笔迹样本中的五种假象不容忽视

研究笔迹样本的一些特征,它既不是代表书写人的书写习惯,也不是书写人笔迹特征的本来面目,对此称之为特征假象。本文拟就对笔迹样本中产生假象的原因、表现形式(除意外产生)进行了研究,并对识别的办法进行探讨。     

Encounters with panaceas: reading flyers and posters on ‘traditional’ healing – a reply to Kadenge and Ndlovu (2012)

Kadenge and Ndlovu [2012. “Encounters with Panaceas: Reading Flyers and Posters on ‘Traditional’ Healing in and Around Johannesburg's Central Business District.” Journal of Contemporary African Studies 30 (3): 461–482] evaluated flyers and posters that advertise traditional and alternative healing methods which they regard as viable alternatives to biomedicine that may well transmit potent knowledge and facilitate new ways of thinking. They furthermore view these flyers and posters as a demonstration of the advertisers’ ‘adaptability’ and ‘sensitivity’ towards their customers (480–481). This article is a rebuttal of the aforementioned position towards, and judgement of these advertisers. Reading these flyers and posters from a misleading advertising and Kantian perspective reveals not a demonstration of adaptability, but rather dishonesty and exploitation; rather than transmitting ancient knowledge, they reinforce superstition and fear. These advertisements, often misleadingly clad as African, do not facilitate new ways of thinking, but merely facilitate deception.