Estimation of a probability in inverse binomial sampling under normalized linear-linear and inverse-linear loss

Sequential estimation of the success probability $p$ in inverse binomial sampling is considered in this paper. For any estimator $\hat p$, its quality is measured by the risk associated with normalized loss functions of linear-linear or inverse-linear form. These functions are possibly asymmetric, with arbitrary slope parameters $a$ and $b$ for $\hat pp$ respectively. Interest in these functions is motivated by their significance and potential uses, which are briefly discussed. Estimators are given for which the risk has an asymptotic value as $p$ tends to $0$, and which guarantee that, for any $p$ in $(0,1)$, the risk is lower than its asymptotic value. This allows selecting the required number of successes, $r$, to meet a prescribed quality irrespective of the unknown $p$. In addition, the proposed estimators are shown to be approximately minimax when $a/b$ does not deviate too much from $1$, and asymptotically minimax as $r$ tends to infinity when $a=b$.Comment: 4 figure

Different Assay Conditions for Detecting the Production and Release of Heat-Labile and Heat-Stable Toxins in Enterotoxigenic Escherichia coli Isolates

Enterotoxigenic Escherichia coli (ETEC) produce heat-labile (LT) and/or heat-stable enterotoxins (ST). Despite that, the mechanism of action of both toxins are well known, there is great controversy in the literature concerning the in vitro production and release of LT and, for ST, no major concerns have been discussed. Furthermore, the majority of published papers describe the use of only one or a few ETEC isolates to define the production and release of these toxins, which hinders the detection of ETEC by phenotypic approaches. Thus, the present study was undertaken to obtain a better understanding of ST and LT toxin production and release under laboratory conditions. Accordingly, a collection of 90 LT-, ST-, and ST/LT-producing ETEC isolates was used to determine a protocol for toxin production and release aimed at ETEC detection. for this, we used previously raised anti-LT antibodies and the anti-ST monoclonal and polyclonal antibodies described herein. the presence of bile salts and the use of certain antibiotics improved ETEC toxin production/release. Triton X-100, as chemical treatment, proved to be an alternative method for toxin release. Consequently, a common protocol that can increase the production and release of LT and ST toxins could facilitate and enhance the sensitivity of diagnostic tests for ETEC using the raised and described antibodies in the present work.Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Butantan Inst, Bacteriol Lab, BR-05503900 São Paulo, BrazilSão Paulo Trop Med Inst, Seroepidemiol & Immunol Lab, BR-05403000 São Paulo, BrazilFleury Med & Hlth, BR-04344903 São Paulo, BrazilButantan Inst, Immunopathol Lab, BR-05503900 São Paulo, BrazilButantan Inst, Immunochem Lab, BR-05503900 São Paulo, BrazilAdolfo Lutz Inst, Bacteriol Sect, BR-01246000 São Paulo, BrazilUniversidade Federal de São Paulo, Escola Paulista Med, Dept Microbiol, BR-04923062 São Paulo, SP, BrazilUniversidade Federal de São Paulo, Escola Paulista Med, Dept Microbiol, BR-04923062 São Paulo, SP, BrazilWeb of Scienc

Analysis of incomplete blocks for rankings

Each of b judges independently rank kh out of t objects, h = 1, 2, ... , b. This basic design is replicated n times, resulting in nb independent blocks. The methods introduced in Alvo and Cabilio (1991) to test for concordance among the judges in a BIBD are extended to this situation and applied to a statistic based on Kendall's tau. This statistic is then analyzed for a situation not considered in Alvo and Cabilio (1991), and it is shown to maintain its superior efficiency over the Durbin test.Incomplete blocks Balanced Doubly balanced Ranking Spearman correlation Kendall correlation Asymptotic distributions Bahadur efficiency