likelihood

可能性
  • 文章类型: Journal Article
    对低温-EM图的解释通常包括对接组件的已知或预测结构,当地图分辨率差于4µ时,这是特别有用的。尽管搜索整个地图以找到组件的最佳位置可能是有效的,当地图很大时,这个过程可能很慢。然而,通常,关于特定组件的位置有一个有充分根据的假设。在这种情况下,使用地图子卷的本地搜索将快得多,因为搜索量较小,并且更敏感,因为优化旋转搜索步骤的搜索量增强了信噪比。一种基于傅里叶空间似然的局部搜索方法,基于先前发布的em_placement软件,已在新的emplace_local程序中实现。测试证实,本地搜索方法提高了计算的速度和灵敏度。ChimeraX分子图形程序中的交互式图形界面提供了一种方便的方法来设置和评估对接计算,特别是在定义地图中应该放置组件的部分时。
    The interpretation of cryo-EM maps often includes the docking of known or predicted structures of the components, which is particularly useful when the map resolution is worse than 4 Å. Although it can be effective to search the entire map to find the best placement of a component, the process can be slow when the maps are large. However, frequently there is a well-founded hypothesis about where particular components are located. In such cases, a local search using a map subvolume will be much faster because the search volume is smaller, and more sensitive because optimizing the search volume for the rotation-search step enhances the signal to noise. A Fourier-space likelihood-based local search approach, based on the previously published em_placement software, has been implemented in the new emplace_local program. Tests confirm that the local search approach enhances the speed and sensitivity of the computations. An interactive graphical interface in the ChimeraX molecular-graphics program provides a convenient way to set up and evaluate docking calculations, particularly in defining the part of the map into which the components should be placed.
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  • 文章类型: Journal Article
    对于涉及copulas的多元非高斯,似然推断由中间的数据主导,拟合模型对于联合尾部推断可能不是很好,例如评估尾部依赖的强度。当初步数据和似然分析表明不对称尾部依赖时,提出了一种基于联合上下尾改进极值推断的方法。使用先前关于尾部依赖性的信息的先验可以与可能性结合使用。结合先验和似然性(在实践中存在一定程度的错误指定)来获得倾斜的对数似然性,具有适当变换参数的推断可以基于贝叶斯计算方法或倾斜对数似然的数值优化,以获得后验模式和该模式下的Hessian。
    For multivariate non-Gaussian involving copulas, likelihood inference is dominated by the data in the middle, and fitted models might not be very good for joint tail inference, such as assessing the strength of tail dependence. When preliminary data and likelihood analysis suggest asymmetric tail dependence, a method is proposed to improve extreme value inferences based on the joint lower and upper tails. A prior that uses previous information on tail dependence can be used in combination with the likelihood. With the combination of the prior and the likelihood (which in practice has some degree of misspecification) to obtain a tilted log-likelihood, inferences with suitably transformed parameters can be based on Bayesian computing methods or with numerical optimization of the tilted log-likelihood to obtain the posterior mode and Hessian at this mode.
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  • 文章类型: Journal Article
    生存分析的格局不断被彻底改变,以应对生物医学挑战,最近的统计挑战是审查协变量而不是结果。有许多有前途的策略来解决审查的协变量,包括加权,imputation,最大似然,和贝叶斯方法。尽管如此,这是一个比较新鲜的研究领域,与审查结果的领域不同(即,生存分析)或缺失协变量。在这次审查中,我们讨论了处理删失协变量时遇到的独特统计挑战,并对旨在解决这些挑战的现有方法进行了深入回顾.我们强调每种方法的相对优势和劣势,提供建议,帮助研究者查明处理数据中删失协变量的最佳方法。
    The landscape of survival analysis is constantly being revolutionized to answer biomedical challenges, most recently the statistical challenge of censored covariates rather than outcomes. There are many promising strategies to tackle censored covariates, including weighting, imputation, maximum likelihood, and Bayesian methods. Still, this is a relatively fresh area of research, different from the areas of censored outcomes (i.e., survival analysis) or missing covariates. In this review, we discuss the unique statistical challenges encountered when handling censored covariates and provide an in-depth review of existing methods designed to address those challenges. We emphasize each method\'s relative strengths and weaknesses, providing recommendations to help investigators pinpoint the best approach to handling censored covariates in their data.
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  • 文章类型: Journal Article
    准确模拟人体生理系统的数学模型是推进医学科学和促进创新临床干预的基石工具。一种应用是声门下和颈部皮肤特性的建模,用于声带功能的动态评估,通过颈部表面加速度计实现声门气流的非侵入性监测。为了使技术有效,需要开发声门下束的精确积木模型。预期这样的模型利用声门体积速度作为输入参数,并产生颈部皮肤加速度作为相应的输出。与之前采用频域方法的努力相比,本文利用系统识别技术,使用时域数据样本得出声门下道的简约连续时间模型。此外,通过应用各种信息标准对模型订单进行检查。一旦低阶模型被成功拟合,基于卡尔曼平滑器的逆滤波器用于估计声门速度和相关的空气动力学指标,从而构成了迄今为止这些估计的最有效执行。由于声门下模型的较低阶而导致的计算时间和复杂性的预期减少对于实时监测具有特别的相关性。同时,该方法被证明可以有效地生成一系列动态声乐功能评估所必需的空气动力学特征。
    Mathematical models that accurately simulate the physiological systems of the human body serve as cornerstone instruments for advancing medical science and facilitating innovative clinical interventions. One application is the modeling of the subglottal tract and neck skin properties for its use in the ambulatory assessment of vocal function, by enabling non-invasive monitoring of glottal airflow via a neck surface accelerometer. For the technique to be effective, the development of an accurate building block model for the subglottal tract is required. Such a model is expected to utilize glottal volume velocity as the input parameter and yield neck skin acceleration as the corresponding output. In contrast to preceding efforts that employed frequency-domain methods, the present paper leverages system identification techniques to derive a parsimonious continuous-time model of the subglottal tract using time-domain data samples. Additionally, an examination of the model order is conducted through the application of various information criteria. Once a low-order model is successfully fitted, an inverse filter based on a Kalman smoother is utilized for the estimation of glottal volume velocity and related aerodynamic metrics, thereby constituting the most efficient execution of these estimates thus far. Anticipated reductions in computational time and complexity due to the lower order of the subglottal model hold particular relevance for real-time monitoring. Simultaneously, the methodology proves efficient in generating a spectrum of aerodynamic features essential for ambulatory vocal function assessment.
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  • 文章类型: Journal Article
    2×2列联表的分类数据分析非常普遍,尤其是因为它们提供了风险差异,风险比率,赔率比,和记录医学研究中的赔率统计。最常用的是χ2检验分析,尽管一些研究人员使用似然比检验(LRT)分析。使用哪种测试有关系吗?文献综述,考察理论基础,本文使用模拟和经验数据的分析来论证,当我们有兴趣测试二项式比例是否相等时,只能使用LRT。这种所谓的独立性测试是迄今为止最受欢迎的,这意味着χ2检验被广泛误用。相比之下,χ2检验应保留用于数据似乎与特定假设过于匹配的地方(例如,零假设),其中方差是感兴趣的,并且低于预期。在各种情况下,低方差可能会引起人们的兴趣,特别是在数据完整性的调查中。最后,有人认为,证据方法提供了一种一致和连贯的方法,避免了显著性检验带来的困难。该方法有助于计算适当的对数似然比,以满足我们的研究目的,无论是测试比例还是测试方差。本文的结论适用于更大的列联表,包括多路表。
    Categorical data analysis of 2 × 2 contingency tables is extremely common, not least because they provide risk difference, risk ratio, odds ratio, and log odds statistics in medical research. A χ2 test analysis is most often used, although some researchers use likelihood ratio test (LRT) analysis. Does it matter which test is used? A review of the literature, examination of the theoretical foundations, and analyses of simulations and empirical data are used by this paper to argue that only the LRT should be used when we are interested in testing whether the binomial proportions are equal. This so-called test of independence is by far the most popular, meaning the χ2 test is widely misused. By contrast, the χ2 test should be reserved for where the data appear to match too closely a particular hypothesis (e.g., the null hypothesis), where the variance is of interest, and is less than expected. Low variance can be of interest in various scenarios, particularly in investigations of data integrity. Finally, it is argued that the evidential approach provides a consistent and coherent method that avoids the difficulties posed by significance testing. The approach facilitates the calculation of appropriate log likelihood ratios to suit our research aims, whether this is to test the proportions or to test the variance. The conclusions from this paper apply to larger contingency tables, including multi-way tables.
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  • 文章类型: Journal Article
    普遍的共识是,自闭症的感觉-知觉差异,例如对光或声音过敏,由于过度依赖新的(而不是先前的)感官观察。然而,对于这种改变是由更精确的感官观察(精确似然模型)还是由较不精确的感官背景模型(低先验模型)引起的,自闭症的贝叶斯解释仍未解决。我们使用了不确定性下的决策范式,该范式操纵了可能性和先验的不确定性。与模型预测相反,我们发现自闭症患者(AS)与神经典型患者(NT)相比,对可能性的依赖没有差异,并且两组之间的主观先验方差也没有差异。然而,我们发现与NT相比,AS组的背景调整减少.Further,AS组在感觉信息的相对权重上表现出高度的变异性(与事先)在逐个审判的基础上。当参与者在自闭症特征的连续性上保持一致时,我们发现与似然依赖或先验方差无关联,但发现与自闭症特征的似然精度增加.这些发现共同为完整的前科提供了经验证据,精确的可能性,自闭症感觉学习过程中上下文更新减少,变异性增加。
    A general consensus persists that sensory-perceptual differences in autism, such as hypersensitivities to light or sound, result from an overreliance on new (rather than prior) sensory observations. However, conflicting Bayesian accounts of autism remain unresolved as to whether such alterations are caused by more precise sensory observations (precise likelihood model) or by forming a less precise model of the sensory context (hypo-priors model). We used a decision-under-uncertainty paradigm that manipulated uncertainty in both likelihoods and priors. Contrary to model predictions we found no differences in reliance on likelihood in autistic group (AS) compared to neurotypicals (NT) and found no differences in subjective prior variance between groups. However, we found reduced context adjustment in the AS group compared to NT. Further, the AS group showed heightened variability in their relative weighting of sensory information (vs. prior) on a trial-by-trial basis. When participants were aligned on a continuum of autistic traits, we found no associations with likelihood reliance or prior variance but found an increase in likelihood precision with autistic traits. These findings together provide empirical evidence for intact priors, precise likelihood, reduced context updating and heightened variability during sensory learning in autism.
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  • 文章类型: Journal Article
    医疗诊断在患者护理和医疗保健中的作用至关重要。建立的诊断实践通常依赖于预定的临床标准和数值阈值。相比之下,贝叶斯推理提供了一个先进的框架,通过深入的概率分析支持诊断。本研究的目的是引入一个软件工具,致力于在贝叶斯诊断的不确定性的量化,一个迄今为止探索很少的领域。提出的工具,免费提供的专业软件程序,利用不确定性传播技术来估计采样,测量,以及疾病后验概率的组合不确定性。它具有两个主要模块和十五个子模块,所有这些都旨在促进对患病和非患病人群样本的后验概率估计的标准不确定性的估计和图形表示,纳入参数,如测试被测量的平均值和标准偏差,样品的大小,以及筛选和诊断测试固有的标准测量不确定度。我们的研究通过检查来自国家健康和营养检查调查的空腹血糖数据来展示该程序的实际应用。探索了参数分布模型来评估糖尿病的贝叶斯后验概率的不确定性,使用口服葡萄糖耐量试验作为参考诊断方法。
    The role of medical diagnosis is essential in patient care and healthcare. Established diagnostic practices typically rely on predetermined clinical criteria and numerical thresholds. In contrast, Bayesian inference provides an advanced framework that supports diagnosis via in-depth probabilistic analysis. This study\'s aim is to introduce a software tool dedicated to the quantification of uncertainty in Bayesian diagnosis, a field that has seen minimal exploration to date. The presented tool, a freely available specialized software program, utilizes uncertainty propagation techniques to estimate the sampling, measurement, and combined uncertainty of the posterior probability for disease. It features two primary modules and fifteen submodules, all designed to facilitate the estimation and graphical representation of the standard uncertainty of the posterior probability estimates for diseased and non-diseased population samples, incorporating parameters such as the mean and standard deviation of the test measurand, the size of the samples, and the standard measurement uncertainty inherent in screening and diagnostic tests. Our study showcases the practical application of the program by examining the fasting plasma glucose data sourced from the National Health and Nutrition Examination Survey. Parametric distribution models are explored to assess the uncertainty of Bayesian posterior probability for diabetes mellitus, using the oral glucose tolerance test as the reference diagnostic method.
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  • 文章类型: Journal Article
    贝叶斯决策理论认为,最优决策应该使用和权衡先验信念与当前信息,根据他们的相对不确定性。然而,边缘性人格障碍(BPD)患者的一些特征,如快速,对自己和他人的整体看法发生了巨大变化,表明他们可能对前科的依赖不足。这里,我们调查了BPD患者在依赖或结合现有信息方面是否存在一般缺陷.我们通过让BPD患者(n=23)和健康对照(n=18)执行具有不同水平的先前和当前信息不确定性的硬币捕捉感觉运动任务来分析这一点。我们的结果表明,BPD患者学习并使用了先验信息,并以类似贝叶斯的方式将其与当前信息结合起来。我们的研究结果表明,至少在较低的层次上,非社会感觉运动任务,BPD患者可以适当地使用先前和当前的信息,说明使用先验的潜在缺陷可能不是普遍的或领域通用的。
    Bayesian decision theory suggests that optimal decision-making should use and weigh prior beliefs with current information, according to their relative uncertainties. However, some characteristics of borderline personality disorder (BPD) patients, such as fast, drastic changes in the overall perception of themselves and others, suggest they may be underrelying on priors. Here, we investigated if BPD patients have a general deficit in relying on or combining prior with current information. We analyzed this by having BPD patients (n = 23) and healthy controls (n = 18) perform a coin-catching sensorimotor task with varying levels of prior and current information uncertainty. Our results indicate that BPD patients learned and used prior information and combined it with current information in a qualitatively Bayesian-like way. Our results show that, at least in a lower-level, nonsocial sensorimotor task, BPD patients can appropriately use both prior and current information, illustrating that potential deficits using priors may not be widespread or domain-general.
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  • 文章类型: Journal Article
    在像加拿大运动会这样的精英级别比赛中受伤,经常发生,受伤历史是未来受伤的最强预测因素之一;然而,这个协会在加拿大奥运会上是未知的。
    确定受伤史与加拿大运动会比赛中下肢关节损伤发生率之间的关联。
    2009-2019年加拿大运动会(8710名男性和8391名女性运动员)比赛的数据被加拿大运动会理事会取消识别以进行分析。清洁损伤数据并针对先前的损伤和损伤类型和位置进行分类。受伤史是自我报告的,包括脑震荡,主要外科手术,脖子和背部,关节或骨骼创伤,以及韧带或肌腱的创伤。加拿大运动会比赛的伤害被归类为脚踝,膝盖,臀部,髌股关节损伤.独立性的卡方(χ2)检验确定了加拿大运动会比赛期间受伤史与下肢关节损伤发生率之间的关联。IBMSPSS(版本26)用于统计分析(p值<0.05)。
    四百七十五个脚踝,503膝盖,253臀部,在10年的加拿大运动会比赛中,报告了106例髌股关节受伤。颈部和背部受伤的病史与脚踝受伤和膝盖受伤之间存在显着关联,创伤和韧带或肌腱过度使用伴髋关节损伤的病史,以及创伤或关节或骨过度使用伴髌股关节损伤的病史。
    这些发现支持以前的文献表明损伤史与未来损伤有关。
    3.
    UNASSIGNED: Injuries during elite level competition like the Canada Games, occur frequently and injury history is one of the strongest predictors of future injury; however, this association is unknown in the Canada Games.
    UNASSIGNED: To determine the association between injury history and incidence of lower extremity joint injury during Canada Games competition.
    UNASSIGNED: Data from the 2009 - 2019 Canada Games (8710 male and 8391 female athletes) competitions were de-identified by the Canada Games Council for analysis. Injury data were cleaned and categorized for previous injury and injury type and location. Injury history was self-reported and included concussion, major surgical procedure, neck and back, trauma to joint or bone, and trauma to ligament or tendon. Injury from the Canada Games competitions were categorized to include ankle, knee, hip, and patellofemoral joint injuries. Chi-Square (χ2 ) test of independence determined association between injury history and incidence of lower extremity joint injury during Canada Games competition. IBM SPSS (Version 26) was used for statistical analysis (p-value < 0.05).
    UNASSIGNED: Four hundred and seventy-five ankle, 503 knee, 253 hip, and 106 patellofemoral joint injuries were reported during 10 years of Canada Games competitions. There were significant associations between history of neck and back injuries with ankle injuries and knee injuries, history of trauma and overuse of ligament or tendon with hip injuries and history of trauma or overuse of joint or bone with patellofemoral joint injuries.
    UNASSIGNED: These findings support previous literature suggesting that injury history is associated with future injury.
    UNASSIGNED: 3.
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  • 文章类型: Journal Article
    医学诊断是医疗保健中治疗和管理决策的基础。用于医学诊断的常规方法通常使用建立的临床标准和固定的数值阈值。这种方法的局限性可能导致无法捕获诊断测试与疾病的不同患病率之间的复杂关系。为了进一步探索这一点,我们开发了一种免费的专业计算工具,该工具采用贝叶斯推理来计算疾病诊断的后验概率。这个新颖的软件包括三个不同的模块,每个旨在允许用户有效地定义和比较参数和非参数分布。该工具用于分析从两个单独的诊断测试中生成的数据集,每个都在患病和非患病人群中进行。我们通过分析空腹血糖来证明该软件的实用性,和糖化血红蛋白A1c数据来自国家健康和营养检查调查。我们的结果使用口服葡萄糖耐量试验作为参考标准进行验证,我们探索了用于糖尿病贝叶斯诊断的参数和非参数分布模型。
    Medical diagnosis is the basis for treatment and management decisions in healthcare. Conventional methods for medical diagnosis commonly use established clinical criteria and fixed numerical thresholds. The limitations of such an approach may result in a failure to capture the intricate relations between diagnostic tests and the varying prevalence of diseases. To explore this further, we have developed a freely available specialized computational tool that employs Bayesian inference to calculate the posterior probability of disease diagnosis. This novel software comprises of three distinct modules, each designed to allow users to define and compare parametric and nonparametric distributions effectively. The tool is equipped to analyze datasets generated from two separate diagnostic tests, each performed on both diseased and nondiseased populations. We demonstrate the utility of this software by analyzing fasting plasma glucose, and glycated hemoglobin A1c data from the National Health and Nutrition Examination Survey. Our results are validated using the oral glucose tolerance test as a reference standard, and we explore both parametric and nonparametric distribution models for the Bayesian diagnosis of diabetes mellitus.
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