Binomial Confidence Intervals and Contingency Tests: Mathematical Fundamentals and the Evaluation of Alternative Methods

Many statistical methods rely on an underlying mathematical model of probability based on a simple approximation, one that is simultaneously well-known and yet frequently misunderstood. The Normal approximation to the Binomial distribution underpins a range of statistical tests and methods, including the calculation of accurate confidence intervals, performing goodness of fit and contingency tests, line- and model-fitting, and computational methods based upon these. A common mistake is in assuming that, since the probable distribution of error about the “true value” in the population is approximately Normally distributed, the same can be said for the error about an observation. This paper is divided into two parts: fundamentals and evaluation. First, we examine the estimation of confidence intervals using three initial approaches: the “Wald” (Normal) interval, the Wilson score interval and the “exact” Clopper-Pearson Binomial interval. Whereas the first two can be calculated directly from formulae, the Binomial interval must be approximated towards by computational search, and is computationally expensive. However this interval provides the most precise significance test, and therefore will form the baseline for our later evaluations. We also consider two further refinements: employing log-likelihood in intervals (also requiring search) and the effect of adding a continuity correction. Second, we evaluate each approach in three test paradigms. These are the single proportion interval or 2 × 1 goodness of fit test, and two variations on the common 2 × 2 contingency test. We evaluate the performance of each approach by a “practitioner strategy”. Since standard advice is to fall back to “exact” Binomial tests in conditions when approximations are expected to fail, we report the proportion of instances where one test obtains a significant result when the equivalent exact test does not, and vice versa, across an exhaustive set of possible values. We demonstrate that optimal methods are based on continuity-corrected versions of the Wilson interval or Yates’ test, and that commonly-held beliefs about weaknesses of tests are misleading. Log-likelihood, often proposed as an improvement on , performs disappointingly. Finally we note that at this level of precision we may distinguish two types of 2 2 test according to whether the independent variable partitions data into independent populations, and we make practical recommendations for their use

Cooling and recombination processes in cometary plasma

The ion electron plasma in comets is examined for cooling processes which result from its interactions with the neutral coma. A cometary coma model is formulated that is composed predominantly of H2O and its decomposition products where electrons are cooled in a variety of processes at rates varying with energy. It is shown that solar plasma plus accumulated cometary ions and electrons is affected very strongly as it flows into the coma. The electrons are rapidly cooled and all but some 10% of the ions undergo charge exchange. Photodissociation of H2O is assumed where ion electron recombination is the dominant loss process

From respect to reburial: negotiating pagan interest in prehistoric human remains in Britain, through the Avebury consultation

The recent Avebury Consultation on reburial has drawn considerable public and professional attention to the issue of pagan calls for respect towards the care of human remains. Our work has pointed to the importance of archaeologists and others engaging seriously and respectfully with pagans as significant stakeholders in our heritage. The Avebury Reburial Consultation suggests this dialogue is increasing in strength, but we identify problems in the process. We focus here on approaches to the prehistoric dead and worldviews enabling communication from which calls or ‘claims’ for the reburial of prehistoric pagan human remains, versus their retention for scientific study, are articulated; frameworks for assessing and adjudicating such ‘claims’; and implications for the interest groups concerned. We argue that room must be made for philosophical debate and the emotional and spiritual views of pagans, in order to improve dialogue, develop common ground, and enable participatory decision-making and situational pragmatism

Statistical Properties of Interacting Bose Gases in Quasi-2D Harmonic Traps

The analytical probability distribution of the quasi-2D (and purely 2D) ideal and interacting Bose gas are investigated by using a canonical ensemble approach. Using the analytical probability distribution of the condensate, the statistical properties such as the mean occupation number and particle number fluctuations of the condensate are calculated. Researches show that there is a continuous crossover of the statistical properties from a quasi-2D to a purely 2D ideal or interacting gases. Different from the case of a 3D Bose gas, the interaction between atoms changes in a deep way the nature of the particle number fluctuations.Comment: RevTex, 10pages, 4 figures, E-mail: [email protected]

Cross-Sectional Survey on the Dengue Knowledge, Attitudes and Preventive Practices Among Students and Staff of a Public University in Malaysia.

Behavioural impact programmes are especially effective for dengue control and prevention. Universities are key settings for health promotion, so understanding factors that influence the practice of dengue prevention within a university community becomes important. This study aimed to examine the factors affecting dengue knowledge, attitude and preventive practices amongst students and staff of a public university. A cross-sectional survey study was conducted in Kuala Lumpur, Malaysia. A total of 372 students and staff of the NDUM were recruited by stratified sampling method. Data were collected via self-administered pre-tested structured questionnaires covering socio-demography and dengue KAP. Data were analysed descriptively. For bivariate analysis, Chi square test was applied. To explore the factors independently associated with the practice of dengue prevention, a logistic regression model was introduced. Overall, the participants had moderate dengue-related knowledge, good attitudes and good preventive practices. The majority had misconceptions about mosquito biting habits (83.8 %), seasonality of dengue epidemics (73.2 %), and mosquito breeding sites (70.3 %). Staff were more likely to have good dengue-related knowledge (p < 0.001) and attitudes (p = 0.008) than students. There was statistically significant positive association between the level of dengue knowledge and monthly average household income (p = 0.008), age (p < 0.001) and education (p < 0.001). Having good attitudes towards dengue was associated with being a non-Malay (p = 0.034), having higher monthly average household income (p = 0.047) and tertiary education (p < 0.001). In regression analysis, only dengue knowledge and dengue attitudes were significantly and positively associated with practice of dengue prevention. Dengue preventive strategies amongst university students and staff should focus on maintaining good dengue-related preventive practices. Educational campaigns should mainly target students, young staff members, and those with lower level of education and income

Interactive Translation vs. Pre-Translation in TMs: A Pilot Study

Translation clients today are looking for high productivity and quality, but are looking for these at reduced costs. Translation Memory (TM) systems are currently among the most popular translation tools on the market and are intended to help translators produce more translations in a short time period while maintaining high quality and consistency in their work. There are two ways of working with a TM system: interactive mode and pre-translation mode. However, there have been no studies to date which attempt to determine whether one mode is superior to the other. This paper describes a pilot study which investigates which of the two produces better results in terms of productivity, quality and translator satisfaction.Les mémoires de traduction (MT) sont présentement l’un des outils de traduction les plus convoités sur le marché. Aujourd’hui, les clients recherchent la productivité et la qualité, sans que cela affecte de façon négative leurs revenus. Deux méthodes s’offrent à l’utilisateur lors de la traduction avec une MT : la traduction interactive et la pré-traduction. Jusqu’à maintenant, on ignore si le choix entre la traduction interactive et la pré-traduction produit un effet sur la productivité, la qualité et la satisfaction du traducteur. Le présent article se propose d’analyser les deux méthodes de traduction avec MT à l’aide d’une méthodologie comparative

Just passing through: Archaeological investigations of a late Holocene open site in the Mitchell Grass Downs, inland northwest Queensland

Comparatively little is known about the archaeology of the Mitchell Grass Downs region of inland Queensland. This paper reports the results of investigations of an open site complex therein, comprising numerous hearths, a human burial, middens, stone arrangements and a stone artefact assemblage. Analysis reveals the stone artefact assemblage is a palimpsest, representing multiple events in the late Holocene compressed into a single non-stratified archaeological surface assemblage. The evidence suggests use of the area was by highly mobile, transient populations passing through on an occasional seasonal basis when environmental conditions were amenable to travel; suggestions for a semi-sedentary population are not supported. Clear evidence for the extensive removal, weathering, reuse and recycling of artefacts has implications for our ability to reconstruct past human behaviours and landscape use in this region

De Novo Genome Sequence of "Candidatus Liberibacter solanacearum" from a Single Potato Psyllid in California.

The draft genome sequence of "Candidatus Liberibacter solanacearum" strain RSTM from a potato psyllid (Bactericera cockerelli) in California is reported here. The RSTM strain has a genome size of 1,286,787 bp, a G+C content of 35.1%, 1,211 predicted open reading frames (ORFs), and 43 RNA genes