A Maximum Test for the Analysis of Ordered Categorical Data

Different scoring schemes are possible when performing exact tests using scores on ordered categorical data. The standard scheme is based on integer scores, but non-integer scores were proposed to increase power (Ivanova & Berger, 2001). However, different non-integer scores exist and the question arises as to which of the non-integer schemes should be chosen. To solve this problem, a maximum test is proposed. To be precise, the maximum of the competing statistics is used as the new test statistic, rather than arbitrarily choosing one single test statistic

The complementarity of astrometric and radial velocity exoplanet observations - Determining exoplanet mass with astrometric snapshots

We obtain full information on the orbital parameters by combining radial velocity and astrometric measurements by means of Bayesian inference. We sample the parameter probability densities of orbital model parameters with a Markov chain Monte Carlo (McMC) method in simulated observational scenarios to test the detectability of planets with orbital periods longer than the observational timelines. We show that, when fitting model parameters simultaneously to measurements from both sources, it is possible to extract much more information from the measurements than when using either source alone. We demonstrate this by studying the orbit of recently found extra-solar planet HD 154345 b.Comment: 6 pages, 9 figures. Accepted to A&

An Equivalence Test Based on \u3cem\u3en\u3c/em\u3e and \u3cem\u3ep\u3c/em\u3e

An equivalence test is proposed which is based on the P-value of a test for a difference and the sample size. This test may be especially appropriate for an exploratory re-analysis if only a non-significant test for a difference was reported. Thus, neither a confidence interval is available, nor is there access to the raw data. The test is illustrated using two examples; for both applications the smallest equivalence range for which equivalence could be demonstrated is calculated

Safety of Eurycoma longifolia (Tongkat Ali) root extract as a novel food pursuant to Regulation (EU) 2015/2283

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Safety of Eurycoma longifolia (Tongkat Ali) root extract as a novel food pursuant to Regulation (EU) 2015/2283

[EN]Following a request from the European Commission, the EFSA Panel on Nutrition, Novel Foods and Food Allergens (NDA) was asked to deliver an opinion on Eurycoma longifolia (Tongkat Ali) root extract as a novel food (NF) pursuant to Regulation (EU) 2015/2283. The NF is standardised water extract prepared from the dried ground root chips of Tongkat Ali (Eurycoma longifolia Jack) and proposed by the applicant to be used as food supplement in amounts up to 200 mg/day. The target population is the adult population, except pregnant and lactating women. The characteristic components of the NF are glycosaponins (40–65%) and eurycomanone (0.8–1.5%). It can also contain canthin-6-one alkaloids and isoscopoletin (coumarin). The NF has been present in various international markets since 2009. The Panel notes positive results from the submitted in vitro chromosome aberration test, which indicates clastogenic properties of the NF. In the requested follow-up in vivo mammalian alkaline comet assay, the NF induced positive results at the highest dose tested (2,000 mg/kg body weight (bw)) at the tissues of the first site of contact (stomach and duodenum). Histopathological evaluation of the tested tissues indicated that the positive results of the comet assay were rather due to genotoxicity than cytotoxicity. Taken together, the Panel concludes that the NF has the potential to induce DNA damage, which is of concern, particularly locally for tissues that represent first sites of contact. The Panel concludes that the safety of NF has not been established under any condition of use.S

Maximum Tests are Adaptive Permutation Tests

In some areas, e.g., statistical genetics, it is common to apply a maximum test, where the maximum of several competing test statistics is used as a new statistic, and the permutation distribution of the maximum is used for inference. Here, it is shown that maximum tests are special cases of adaptive permutation tests. The 30-year old idea of adaptive statistical tests is more flexible than previously thought when permutation tests are used, and the selector statistic is calculated for every permutation. Because the independence between the selector and the test statistics is no longer needed, the test statistics themselves can be used as selectors. Then, the maximum tests fit into the concept of adaptive tests. In addition to the gained flexibility, maximum tests can be more powerful than classical adaptive tests

A general score-independent test for order-restricted inference

In the analysis of ordered categorical data, the categories are often assigned a set of subjectively chosen order-restricted scores. To overcome the arbitrariness involved in the assignment of the scores, several score-independent tests have been proposed. However, these methods are limited to 2 x K contingency tables, where K is the number of ordered categories. We present an efficiency robust score-independent test that is applicable to more general situations. The test is embedded into a flexible framework for conditional inference and provides a natural generalization of many familiar tests involving ordered categorical data, such as the generalized Cochran-Mantel-Haenszel test for singly or doubly ordered contingency tables, the Page test for randomized block designs and the Tarone-Ware trend test for survival data. The proposed method is illustrated by several numerical examples.</p