Statistical methods

统计方法
  • 文章类型: Review
    这篇综述考虑了与解释过去三十年中发表的300篇关于人体和动物组织暴露于射频电磁场(RF-EMF)可能的遗传毒性影响的论文的混合遗产有关的问题。主要论文回顾了遗传毒性测试共识指南的演变,以及对评估用于健康风险评估的科学研究的系统评价的日益重视。附录通过检查采用彗星测定的遗传毒性出版物的子集,考虑了评估生物效应文献中的一些问题。虽然大多数研究发现暴露没有统计学上显著的影响,相当少的研究(主要是,体内研究)报告了暴露的统计学显着影响。研究的质量是高度可变的;虽然一些研究是精心完成和记录,这些研究均不符合目前公认的准则,例如经济合作与发展组织(OECD)的准则.使用偏倚风险(RoB)标准对研究的评估表明,在这个研究样本中,与低质量的研究相比,较高质量的研究不太可能发现有统计学意义的结果.
    作者得出结论,统计显著性应该只是评估生物效应研究的一个考虑因素。在评估暴露的健康风险时,简单地列出使用零假设测试和统计显著性标准p<0.05确定的“统计”显著效应是误导和无信息的。需要仔细综合证据,包括研究效度的评估,报道的影响的生物学意义,以及研究结果与其他相关研究的一致性。作者建议,未来所有用于人类健康风险评估和文献评估的射频遗传毒性研究应按照公认的质量指南进行。即OECD或类似的基因毒性筛选研究指南和PRISMA或其他公认的文献综述指南。该组中的积极研究应该通过更严格的质量控制来重新进行,以建立结果的可靠性。
    This review considers issues related to interpreting the mixed legacy of >300 papers published during the past three decades on possible genotoxic effects of exposure of human and animal tissues to radiofrequency electromagnetic fields (RF-EMF). The main paper reviews the evolution of consensus guidelines for genotoxicity testing and the increasing emphasis on systematic reviews for evaluation of scientific studies for use in health risk assessments. An Appendix considers some issues in assessing the bioeffects literature by examining a subset of genotoxicity publications that employed the comet assay. While most studies found no statistically significant effects of exposure, a significant minority of studies (chiefly, in vivo studies) reported statistically significant effects of exposure. The quality of the studies was highly variable; while several studies were meticulously done and documented, none of these studies were compliant with currently accepted guidelines such as those of the Organization for Economic Cooperation and Development (OECD). Evaluation of the studies using risk of bias (RoB) criteria showed that, in this sample of studies, higher quality studies were less likely to find statistically significant results than those of lower quality.
    The authors conclude that statistical significance should be only one consideration in evaluation of bioeffects studies. Simply listing \'statistically\' significant effects identified using null hypothesis testing and the criterion p < 0.05 for statistical significance is misleading and uninformative in assessing health risks of exposure. A careful synthesis of evidence is needed, including assessment of study validity, biological significance of reported effects, and coherence of study results with those of other related studies.The authors recommend that all future RF genotoxicity studies intended for use in human health risk assessments and evaluations of the literature should be done in compliance with accepted quality guidelines, i.e. OECD or equivalent guidelines for genotoxicity screening studies and PRISMA or other accepted guideline for reviews of the literature. The positive studies in this group should be redone with tighter quality control to establish the reliability of the findings.
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  • 文章类型: Journal Article
    移植接受者科学登记处(SRTR)于2012年举行了一次共识会议,审查了SRTR用于构建绩效指标的方法,并就如何改进特定计划的报告提出了建议。该共识会议提供了25项建议,分类如下:统计方法,风险调整,结果和数据。在随后的十年中,SRTR已经实施了这些建议中的大多数;本文将对这些建议以及2022年另一次共识会议的计划进行描述。在本文中,SRTR旨在提高移植指标领域的透明度,并在2022年下一次共识会议的规划中指导讨论。新的会议将重新讨论以前的主题,并有更广泛的重点,以改善SRTR提供的指标和信息。读者可尽早就下次共识会议讨论的议题提供反馈意见,通过电子邮件srtr@srtr.org与主题行\"任务5公众意见。\"
    The Scientific Registry of Transplant Recipients (SRTR) held a consensus conference in 2012 that examined methods used by SRTR for constructing performance metrics and made recommendations on how to improve program-specific reports. That consensus conference provided 25 recommendations categorized as follows: statistical methods, risk adjustment, and outcomes and data. During the subsequent decade, SRTR has implemented most of these recommendations; these are described in this article along with plans for another consensus conference in 2022. With the present article, SRTR aims to create transparency in the field of transplant metrics and guide discussion in the planning of the next consensus conference in 2022. The new conference will revisit the previous topics and have a broader focus to improve the metrics and information that SRTR provides. Readers can provide feedback on topics to be discussed at the next consensus conference as early as possible, by emailing srtr@srtr.org with the subject line \"Task 5 Public Comment.\"
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  • 文章类型: Journal Article
    目的:点截取方法是测量全球生态系统中物种覆盖率的最常用方法之一。在这种方法中,对多个点进行采样以确定物种的存在/不存在,当前点的数量除以采样点的总数提供了百分比覆盖率的估计。我们的目的是通过数学分析点截取方法的准确性,并建立其使用指南。
    方法:我们开发了分析点截取方法的公式,并使用模拟证实了它们的有效性。
    结果:我们发现,最大植物直径的至少80%的点截距间距提供了最可靠的结果。我们提供了一个用户友好的电子表格,用于计算现场工作所需的截获数,以及标准偏差,预期偏差,和收集数据的置信区间。
    结论:根据我们的研究结果,我们为建立现场协议提供了多种指南,包括处理稀有物种并结合多个物种的结果。四边形特征(截距间距,点截距的数量)现在可以很容易地计算,以在实地考察之前指导研究设计;实地考察完成后,这种技术的准确性可以(并且应该)在所有使用它的未来生态研究中报告。
    OBJECTIVE: The point-intercept method is one of the most commonly used approaches to measure species cover in ecosystems worldwide. In this approach, multiple points are sampled for presence/absence of a species, and the number of present points divided by the total number of sampled points provides an estimate of percent cover. Our purpose is to mathematically analyze the accuracy of the point-intercept approach and establish guidelines for its use.
    METHODS: We developed formulas that analyze the point-intercept method and confirmed their effectiveness using simulations.
    RESULTS: We find that a point-intercept spacing of at least 80% of the largest plant diameter provides the most reliable results. We present a user-friendly spreadsheet that calculates the number of intercepts needed for fieldwork, as well as the standard deviation, expected deviation, and confidence interval of the collected data.
    CONCLUSIONS: We provide a variety of guidelines for establishing field protocols based on our results, including dealing with rare species and combining results for multiple species. Quadrat characteristics (intercept spacing, number of point intercepts) can now be easily calculated to guide research design prior to fieldwork; after fieldwork is complete, the accuracy of this technique can (and should) be reported in all future ecological studies in which it is used.
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  • 文章类型: Journal Article
    In the context of an increasing number of publications of trial data analysed by Bayesian methods, clinicians need support to better understand Bayesian statistical methods. The existing checklists are intended for people who already know these methods. We aimed to establish and validate a checklist that contains a group of items considered crucial in interpreting the results of a phase III RCT analysed with Bayesian methods.
    A team of biostatisticians created a checklist of previously reported items and additional items identified from a literature review. Using three different articles in three rounds, the items were then validated by residents in anaesthesiology with no skills in statistics.
    Based on an initial item list, three rounds led to a consensus checklist. Eleven items were considered important information to be specified for understanding the validity of the results. Of these, three were considered essential: specification of the prior, source of the prior (when prior is informative), and the effect size point estimate with its credible interval.
    The checklist can help clinicians interpret the results of a phase III randomised clinical trial analysed by Bayesian methods, even clinicians with no particular knowledge of statistics, to ensure that the major elements of the statistical section are present and valid. Care should be taken in interpreting the results of a trial analysed by Bayesian methods that are not reported with these three essential items because the validity of the results cannot be established.
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  • 文章类型: Journal Article
    Introduction: The statistical quality of many trial-based economic evaluations is poor. When conducting trial-based economic evaluations, researchers often turn to national pharmacoeconomic guidelines for guidance. Therefore, this study reviewed which recommendations are currently given by national pharmacoeconomic guidelines on the statistical analysis of trial-based economic evaluations.Areas covered: 40 national pharmacoeconomic guidelines were identified. Data were extracted on the guidelines\' recommendations on how to deal with baseline imbalances, skewed costs, correlated costs and effects, clustering of data, longitudinal data, and missing data in trial-based economic evaluations. Four guidelines (10%) were found to include recommendations on how to deal with baseline imbalances, five (13%) on how to deal with skewed costs, and seven (18%) on how to deal with missing data. Recommendations were very general in nature and recommendations on dealing with correlated costs and effects, clustering of data, and longitudinal data were lacking.Expert opinion: Current national pharmacoeconomic guidelines provide little to no guidance on how to deal with the statistical challenges to trial-based economic evaluations. Since the use of suboptimal statistical methods may lead to biased results, and, therefore, possibly to a waste of scarce resources, national agencies are advised to include more statistical guidance in their pharmacoeconomic guidelines.
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  • 文章类型: Journal Article
    The aim of the study was to identify fungal spores, in particular plant pathogenic fungi, occurring in the air in selected mountain ranges. The results revealed not only the array of fungal species migrating with air currents from the Czech Republic and Slovakia but also how the season of the year affects the distribution of spores. Such studies may lay a foundation for future aeromycological monitoring, in accordance with the requirements for integrated plant protection. Aeromycological research was carried out between 2013 and 2016 at 3-month intervals in mountainous areas along the southern borders of Poland: the Bieszczady, the Pieniny, the Giant Mountains (Karkonosze) and the Babia Góra Massif. The research relied on impact method employing Air Ideal 3P sampler, which, by drawing in atmospheric air, also collects fungal spores. Regardless of altitudinal zonation, the changing weather conditions appeared to be the main reason for the variations in the number of the fungal spores under study in those years.
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