statistical significance

统计意义
  • 文章类型: Journal Article
    在这项工作中,我们提出了一种新的方法来构建全脑时空多层功能连接网络(FCN)和四个创新的丰富俱乐部指标。
    时空多层FCN通过将滑动时间窗方法与图论和超图理论相结合,实现了脑网络时空动态特性的高阶表示。提出的四个丰富俱乐部尺度是基于丰富俱乐部节点身份的动态变化,提供了从时间和空间角度对脑网络的拓扑动态特性的参数化描述。在三个独立差异分析实验中验证了所提出的方法:男女性别差异分析,自闭症谱系障碍(ASD)患者的异常分析,和个体差异分析。
    所提出的方法产生的结果与先前的相关研究一致,并揭示了一些创新的发现。例如,特定白质区域的动态拓扑特征有效地反映了个体差异。基底神经节内部功能连接异常的增加可能是ASD患者重复或限制性行为发生的原因。
    所提出的方法为构建全脑时空多层FCN并对其动态拓扑结构进行分析提供了有效的方法。时空多层FCN的动态拓扑特征可能为神经科学中的生理变异和病理异常提供新的见解。
    UNASSIGNED: In this work, we propose a novel method for constructing whole-brain spatio-temporal multilayer functional connectivity networks (FCNs) and four innovative rich-club metrics.
    UNASSIGNED: Spatio-temporal multilayer FCNs achieve a high-order representation of the spatio-temporal dynamic characteristics of brain networks by combining the sliding time window method with graph theory and hypergraph theory. The four proposed rich-club scales are based on the dynamic changes in rich-club node identity, providing a parameterized description of the topological dynamic characteristics of brain networks from both temporal and spatial perspectives. The proposed method was validated in three independent differential analysis experiments: male-female gender difference analysis, analysis of abnormality in patients with autism spectrum disorders (ASD), and individual difference analysis.
    UNASSIGNED: The proposed method yielded results consistent with previous relevant studies and revealed some innovative findings. For instance, the dynamic topological characteristics of specific white matter regions effectively reflected individual differences. The increased abnormality in internal functional connectivity within the basal ganglia may be a contributing factor to the occurrence of repetitive or restrictive behaviors in ASD patients.
    UNASSIGNED: The proposed methodology provides an efficacious approach for constructing whole-brain spatio-temporal multilayer FCNs and conducting analysis of their dynamic topological structures. The dynamic topological characteristics of spatio-temporal multilayer FCNs may offer new insights into physiological variations and pathological abnormalities in neuroscience.
    导出

    更多引用

    收藏

    翻译标题摘要

    我要上传

       PDF(Pubmed)

  • 文章类型: Journal Article
    这项研究分析了21辆中国VI重型柴油卡车(HDDT)的实际NOx和颗粒数(PN)排放。首先使用便携式排放测量系统(PEMS)评估道路排放符合性。只有76.19%,71.43%和61.90%的车辆通过NOx测试,PN测试和两个测试,分别。包括废气再循环(EGR)设备在内的车辆功能的影响,然后评估里程和牵引吨位。结果表明,EGR有助于降低NOx排放因子(EF),同时增加PNEF。较大的里程和牵引吨位对应较高的NOx和PNEF,分别。通过数值比较和统计测试,对操作条件对排放的影响进行了深入分析。结果证明,HDDT在低速或大车辆比功率(VSP)下产生较高的NOxEF,和更高的PNEF在高速或小VSP一般。此外,不合格车辆产生的NOxEF明显高于高速公路上或车速≥40km/h的合格车辆,虽然郊区道路上产生了显著较高的PNEF,高速公路或不合格车辆在具有正VSP的运行模式下。最后研究了车载诊断(OBD)NOx数据的可靠性和准确性。结果显示,43%的测试车辆没有报告可靠的OBD数据。OBDNOx和PEMS测量之间的相关性分析进一步证明瞬时浓度的一致性通常较低。然而,滑动窗口平均浓度显示出更好的相关性,例如,对于大多数车辆,20s窗口平均浓度的Pearson相关系数超过0.85。研究结果为排放管制提供了有价值的见解,例如,更加注重中高速运行,以识别不合格车辆,设定更高的标准以提高OBD数据的质量,并采用窗口平均OBDNOx浓度评价车辆排放性能。
    This research analyzed the real-world NOx and particle number (PN) emissions of 21 China VI heavy-duty diesel trucks (HDDTs). On-road emission conformity was first evaluated with portable emission measurement system (PEMS). Only 76.19 %, 71.43 % and 61.90 % of the vehicles passed the NOx test, PN test and both tests, respectively. The impacts of vehicle features including exhaust gas recirculation (EGR) equipment, mileage and tractive tonnage were then assessed. Results demonstrated that EGR helped reducing NOx emission factors (EFs) while increased PN EFs. Larger mileages and tractive tonnages corresponded to higher NOx and PN EFs, respectively. In-depth analyses regarding the influences of operating conditions on emissions were conducted with both numerical comparisons and statistical tests. Results proved that HDDTs generated higher NOx EFs under low speeds or large vehicle specific powers (VSPs), and higher PN EFs under high speeds or small VSPs in general. In addition, unqualified vehicles generated significantly higher NOx EFs than qualified vehicles on freeways or under speed≥40 km/h, while significant higher PN EFs were generated on suburban roads, freeways or under operating modes with positive VSPs by unqualified vehicles. The reliability and accuracy of on-board diagnostic (OBD) NOx data were finally investigated. Results revealed that 43 % of the test vehicles did not report reliable OBD data. Correlation analyses between OBD NOx and PEMS measurements further demonstrated that the consistency of instantaneous concentrations were generally low. However, sliding window averaged concentrations show better correlations, e.g., the Pearson correlation coefficients on 20s-window averaged concentrations exceeded 0.85 for most vehicles. The research results provide valuable insights into emission regulation, e.g., focusing more on medium- to high-speed operations to identify unqualified vehicles, setting higher standards to improve the quality of OBD data, and adopting window averaged OBD NOx concentrations in evaluating vehicle emission performance.
    导出

    更多引用

    收藏

    翻译标题摘要

    我要上传

    求助全文

  • 文章类型: Review
    局部关联是指从生物领域出现的时空关联,例如时间依赖性基因共表达或微生物之间的季节性相互作用。通过检查这些关联的生物时间序列数据,可以揭示生物系统的复杂动态和固有相互作用。为了实现这个目标,已经开发了局部相似性分析算法和统计方法,这些算法和方法可以促进时间序列的局部对齐并评估由此产生的对齐的重要性。尽管这些算法最初是为微阵列基因表达分析而设计的,它们已经适应和加速了多组学下一代测序数据集,取得较高的科学影响力。在这次审查中,我们概述了局部相似性分析算法的历史发展和最新进展,它们的统计特性,以及在分析生物时间序列数据方面的实际应用。本审查中使用的基准数据和分析脚本可在http://github.com/labxscut/lsareview上免费获得。
    Local associations refer to spatial-temporal correlations that emerge from the biological realm, such as time-dependent gene co-expression or seasonal interactions between microbes. One can reveal the intricate dynamics and inherent interactions of biological systems by examining the biological time series data for these associations. To accomplish this goal, local similarity analysis algorithms and statistical methods that facilitate the local alignment of time series and assess the significance of the resulting alignments have been developed. Although these algorithms were initially devised for gene expression analysis from microarrays, they have been adapted and accelerated for multi-omics next generation sequencing datasets, achieving high scientific impact. In this review, we present an overview of the historical developments and recent advances for local similarity analysis algorithms, their statistical properties, and real applications in analyzing biological time series data. The benchmark data and analysis scripts used in this review are freely available at http://github.com/labxscut/lsareview.
    导出

    更多引用

    收藏

    翻译标题摘要

    我要上传

    求助全文

  • 文章类型: Journal Article
    自2014年以来,脆弱性指数越来越多地用于评估临床试验结果的稳健性。它旨在找到可以改变最初具有统计学意义的结果的最小数量的事件变化。尽管它很受欢迎,一些研究人员对脆弱性指数的有效性和有用性表示了一些担忧。它全面审查了脆弱性指数的基本原理,计算,软件,和解释,重点是在妇产科研究中的应用。本文介绍了个体临床试验设置中的脆弱性指数,标准的成对荟萃分析,和网络荟萃分析。此外,这篇文章提供了一些实例来演示如何适当地计算和解释脆弱性指数。此外,回顾了传统脆弱性指数的局限性以及文献中针对这些局限性提出的一些解决方案。总之,建议将脆弱性指数作为临床试验报告的补充指标,并作为向临床医师传达试验结果稳健性的工具.有助于脆弱性指数解释的其他考虑因素包括后续行动的损失和数据修改的可能性,这些数据修改会导致统计显著性的损失。
    The fragility index has been increasingly used to assess the robustness of the results of clinical trials since 2014. It aims at finding the smallest number of event changes that could alter originally statistically significant results. Despite its popularity, some researchers have expressed several concerns about the validity and usefulness of the fragility index. It offers a comprehensive review of the fragility index\'s rationale, calculation, software, and interpretation, with emphasis on application to studies in obstetrics and gynecology. This article presents the fragility index in the settings of individual clinical trials, standard pairwise meta-analyses, and network meta-analyses. Moreover, this article provides worked examples to demonstrate how the fragility index can be appropriately calculated and interpreted. In addition, the limitations of the traditional fragility index and some solutions proposed in the literature to address these limitations were reviewed. In summary, the fragility index is recommended to be used as a supplemental measure in the reporting of clinical trials and a tool to communicate the robustness of trial results to clinicians. Other considerations that can aid in the fragility index\'s interpretation include the loss to follow-up and the likelihood of data modifications that achieve the loss of statistical significance.
    导出

    更多引用

    收藏

    翻译标题摘要

    我要上传

       PDF(Pubmed)

  • 文章类型: Journal Article
    目标:建议评估的分级,目前,对不精确的确定性域进行评级的开发和评估(GRADE)指南尚未完全用于将评级降低两个级别,并且考虑了这些风险中的不同基线风险或不确定性。此外,在某些情况下,由于不精确而将证据的确定性降低三个级别比降低两个级别更合适。在这篇文章中,我们将不精确的评级概念化和操作化,使用上下文化的等级方法和做出决策的不精确的两个和三个级别。
    方法:通过在线会议中的迭代讨论和改进以及通过电子邮件通信,我们制定了指南草案,根据例子将证据的确定性降低了三个级别。主要作者根据这些会议期间收到的反馈和评论修改了该方法,并制定了如何应用该方法的GRADE指南。我们向2021年10月GRADE工作组会议的所有与会者(约80人)提供了结果摘要,该方法已正式批准。
    结果:本指南提供了GRADE的新颖方法,用于考虑将不精确评分降低一个,基于严重的两个和三个级别,非常严重和极其严重的关切。该方法包括识别或定义健康结果的阈值,这些阈值对应于微不足道或没有,小,中等或较大的影响,并使用它们来评估不精确。它有助于在决策框架中使用证据,并为如何使用“审查信息大小”的概念和不同的基线风险解决不合理的大影响和微不足道或没有影响的不精确性提供指导。用实际例子说明了该方法,在线计算器和图形显示,可以应用于二分和连续的结果。
    结论:在这篇等级指导文章中,我们提供了有关如何使用部分和完全上下文化的等级方法来评估不精确性的最新指南,以提出建议或决策,考虑替代基线风险,以及二分法和连续结果。
    Grading of Recommendations Assessment, Development and Evaluation (GRADE) guidance to rate the certainty domain of imprecision is presently not fully operationalized for rating down by two levels and when different baseline risk or uncertainty in these risks are considered. In addition, there are scenarios in which lowering the certainty of evidence by three levels for imprecision is more appropriate than lowering it by two levels. In this article, we conceptualize and operationalize rating down for imprecision by one, two and three levels for imprecision using the contextualized GRADE approaches and making decisions.
    Through iterative discussions and refinement in online meetings and through email communication, we developed draft guidance to rating the certainty of evidence down by up to three levels based on examples. The lead authors revised the approach according to the feedback and the comments received during these meetings and developed GRADE guidance for how to apply it. We presented a summary of the results to all attendees of the GRADE Working Group meeting for feedback in October 2021 (approximately 80 people) where the approach was formally approved.
    This guidance provides GRADE\'s novel approach for the considerations about rating down for imprecision by one, two and three levels based on serious, very serious and extremely serious concerns. The approach includes identifying or defining thresholds for health outcomes that correspond to trivial or none, small, moderate or large effects and using them to rate imprecision. It facilitates the use of evidence to decision frameworks and also provides guidance for how to address imprecision about implausible large effects and trivial or no effects using the concept of the \'review information size\' and for varying baseline risks. The approach is illustrated using practical examples, an online calculator and graphical displays and can be applied to dichotomous and continuous outcomes.
    In this GRADE guidance article, we provide updated guidance for how to rate imprecision using the partially and fully contextualized GRADE approaches for making recommendations or decisions, considering alternate baseline risks and for both dichotomous and continuous outcomes.
    导出

    更多引用

    收藏

    翻译标题摘要

    我要上传

    求助全文

  • 文章类型: Journal Article
    生物时间序列数据在探索生物系统动态变化中具有重要作用,而各种生物因素之间的确定关联模式可以进一步加深对生物系统功能及其之间相互作用的理解。目前,局部趋势分析(LTA)已经在许多生物领域普遍进行,其中生物时间序列数据可以是基因表达或OTU丰度水平的序列,等。,局部趋势得分可以通过取向上的相似程度来获得,时间序列数据的恒定或下降趋势,作为不同生物因素之间相关性的指标。然而,局部趋势分析面临的一个主要限制是,为计算其统计显著性而进行的置换检验需要一个耗时的过程。因此,生物信息学家关注的问题是开发一种快速有效地评估局部趋势分数的统计意义的方法。在本文中,提出了一种新的方法来评估相关时间序列的局部趋势分析中统计意义的有效逼近,并通过仿真和实际数据集分析证明了新方法的有效性。
    Biological time series data plays an important role in exploring the dynamic changes of biological systems, while the determinate patterns of association between various biological factors can further deepen the understanding of biological system functions and the interactions between them. At present, local trend analysis (LTA) has been commonly conducted in many biological fields, where the biological time series data can be the sequence at either the level of gene expression or OTU abundance, etc., A local trend score can be obtained by taking the similarity degree of the upward, constant or downward trend of time series data as an indicator of the correlation between different biological factors. However, a major limitation facing local trend analysis is that the permutation test conducted to calculate its statistical significance requires a time-consuming process. Therefore, the problem attracting much attention from bioinformatics scientists is to develop a method of evaluating the statistical significance of local trend scores quickly and effectively. In this paper, a new approach is proposed to evaluate the efficient approximation of statistical significance in the local trend analysis of dependent time series, and the effectiveness of the new method is demonstrated through simulation and real data set analysis.
    导出

    更多引用

    收藏

    翻译标题摘要

    我要上传

       PDF(Pubmed)

  • 文章类型: Journal Article
    There has been a long-standing controversy among scientists regarding the appropriate use of P-values and statistical significance in clinical research. This debate has resurfaced through recent calls to modify the threshold of P-value required to declare significance, or to retire statistical significance entirely. In this article, we revisit the issue by discussing: i) the connection between statistical thinking and evidence-based practice; ii) some history of statistical significance and P-values; iii) some practical challenges with statistical significance or P-value thresholds in clinical research; iv) the on-going debate on what to do with statistical significance; v) suggestions to shift the focus away from binary thinking of statistical significance and towards education for key stakeholders on research essentials including statistical thinking, critical thinking, good reporting, basic clinical research concepts and methods, and more. We then conclude with remarks and illustrations of the potential deleterious public health consequences of poor methods including selective choice of analysis approach and misguided reliance on binary use of P-values to report and interpret scientific findings.
    导出

    更多引用

    收藏

    翻译标题摘要

    我要上传

       PDF(Sci-hub)

  • 文章类型: Journal Article
    A standard pathway/gene-set enrichment analysis, the over-representation analysis, is based on four values: the size of two gene-sets, size of their overlap, and size of the gene universe from which the gene-sets are chosen. The standard result of such an analysis is based on the p-value of a statistical test. We supplement this standard pipeline by six cautions: (1) any p-value threshold to distinguish enriched gene-sets from not-enriched ones is to certain degree arbitrary; (2) genes in a gene-set may be correlated, which potentially overcount the gene-set size; (3) any attempt to impose multiple testing correction will increase the false negative rate; (4) gene-sets in a gene-set database may be correlated, potentially overcount the factor for multiple testing correction; (5) the discrete nature of the data make it possible that a minimum change in counts may lead to a quantum change in the p-value threshold-based conclusion; (6) the two gene-sets may not be chosen from the universe of all human genes, but in fact from a subset of that universe, or even two different subsets of all genes. Careful reconsideration of these issues can have an impact on an enrichment analysis conclusion. Part of our cautions mirror the call from statistician that reaching conclusion from data is not a simple matter of p-value smaller than 0.05, but a thoughtful process with due diligences.
    导出

    更多引用

    收藏

    翻译标题摘要

    我要上传

       PDF(Sci-hub)

  • 文章类型: Journal Article
    Drugs are very important for human life because they can provide treatment, cure, prevention, or diagnosis of different diseases. However, they also cause side effects, which can increase the risks for humans and pharmaceuticals companies. It is essential to identify drug side effects in drug discovery. To date, lots of computational methods have been proposed to predict the side effects of drugs and most of them used the fact that similar drugs always have similar side effects. However, previous studies did not analyze which substructures are highly related to which kind of side effect.
    In this study, we conducted a computational investigation. In this regard, we extracted a drug set for each side effect, which consisted of drugs having the side effect. Also, for each substructure, a set was constructed by picking up drugs owing such substructure. The relationship between one side effect and one substructure was evaluated based on linkages between drugs in their corresponding drug sets, resulting in an Es value. Then, the statistical significance of Es value was measured by a permutation test.
    A number of highly related pairs of side effects and substructures were obtained and some were extensively analyzed to confirm the reliability of the results reported in this study.
    导出

    更多引用

    收藏

    翻译标题摘要

    我要上传

    求助全文

  • 文章类型: Journal Article
    BACKGROUND: Local similarity analysis (LSA) of time series data has been extensively used to investigate the dynamics of biological systems in a wide range of environments. Recently, a theoretical method was proposed to approximately calculate the statistical significance of local similarity (LS) scores. However, the method assumes that the time series data are independent identically distributed, which can be violated in many problems.
    RESULTS: In this paper, we develop a novel approach to accurately approximate statistical significance of LSA for dependent time series data using nonparametric kernel estimated long-run variance. We also investigate an alternative method for LSA statistical significance approximation by computing the local similarity score of the residuals based on a predefined statistical model. We show by simulations that both methods have controllable type I errors for dependent time series, while other approaches for statistical significance can be grossly oversized. We apply both methods to human and marine microbial datasets, where most of possible significant associations are captured and false positives are efficiently controlled.
    CONCLUSIONS: Our methods provide fast and effective approaches for evaluating statistical significance of dependent time series data with controllable type I error. They can be applied to a variety of time series data to reveal inherent relationships among the different factors.
    导出

    更多引用

    收藏

    翻译标题摘要

    我要上传

       PDF(Sci-hub)

       PDF(Pubmed)

公众号