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PubMed Journals Articles About "Control Based Imputation Sensitivity Analyses Informative Censoring Recurrent" RSS

15:36 EST 10th December 2018 | BioPortfolio

Control Based Imputation Sensitivity Analyses Informative Censoring Recurrent PubMed articles on BioPortfolio. Our PubMed references draw on over 21 million records from the medical literature. Here you can see the latest Control Based Imputation Sensitivity Analyses Informative Censoring Recurrent articles that have been published worldwide.

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Showing "Control based imputation sensitivity analyses informative censoring recurrent" PubMed Articles 1–25 of 52,000+

Multiple imputation of missing data in nested case-control and case-cohort studies.

The nested case-control and case-cohort designs are two main approaches for carrying out a substudy within a prospective cohort. This article adapts multiple imputation (MI) methods for handling missing covariates in full-cohort studies for nested case-control and case-cohort studies. We consider data missing by design and data missing by chance. MI analyses that make use of full-cohort data and MI analyses based on substudy data only are described, alongside an intermediate approach in which the imputation...


Imputation-Based HLA Typing with SNPs in GWAS Studies.

SNP-based imputation approaches for human leukocyte antigen (HLA) typing take advantage of the extended haplotype structure within the major histocompatibility complex (MHC) to predict classical HLA alleles using dense SNP genotypes, such as those available on chip panels of genome-wide association study (GWAS). These methods enable HLA analyses of classical alleles on existing SNP datasets genotyped in GWAS studies at no extra cost. Here, I describe the workflow of HIBAG, an imputation method with attribut...

Allowing for uncertainty due to missing and LOCF imputed outcomes in meta-analysis.

The use of the last observation carried forward (LOCF) method for imputing missing outcome data in randomized clinical trials has been much criticized and its shortcomings are well understood. However, only recently have published studies widely started using more appropriate imputation methods. Consequently, meta-analyses often include several studies reporting their results according to LOCF. The results from such meta-analyses are potentially biased and overprecise. We develop methods for estimating summ...


Exploring the Effects of Early Censoring and Analysis of Clinical Trial Survival Data on Effectiveness and Cost-Effectiveness Estimation through a Case Study in Advanced Breast Cancer.

Interim analyses of clinical trial data are frequently used to provide evidence to obtain marketing authorization for new drugs. However, results from such analyses may not reflect true estimates of relative effectiveness when trial follow-up is complete. Survival results, available at 2 time points from a breast cancer clinical trial, were compared to test the hypothesis that using immature data and a widely used right-censoring rule leads to biased survival estimates. Kaplan-Meier progression-free and ove...

A heuristic method for fast and accurate phasing and imputation of single-nucleotide polymorphism data in bi-parental plant populations.

Key message New fast and accurate method for phasing and imputation of SNP chip genotypes within diploid bi-parental plant populations. This paper presents a new heuristic method for phasing and imputation of genomic data in diploid plant species. Our method, called AlphaPlantImpute, explicitly leverages features of plant breeding programmes to maximise the accuracy of imputation. The features are a small number of parents, which can be inbred and usually have high-density genomic data, and few recombinatio...

Influence of imputation strategies on the identification of brain functional connectivity networks.

Whenever neurophysiological data, such as EEG data are recorded, occurring artifacts pose an essential problem. This study addresses this issue by using imputation methods whereby whole data sets of a trial, or distinct electrodes, are not removed from the analysis of the EEG data but are replaced. We present different imputation strategies but use only two which are optimal for this particular study; predictive mean matching and data augmentation. The study addresses the as of yet unresolved question if th...

Methods for Handling Left-Censored Data in Quantitative Microbial Risk Assessment.

Data below detection limits, left-censored data, are common in environmental microbiology, and decisions in handling censored data may have implications for quantitative microbial risk assessment (QMRA). In this paper, we utilize simulated data sets informed by real-world enterovirus water data to evaluate methods for handling left-censored data. Data sets were simulated with four censoring degrees (low (10%), medium (35%), high (65%), and severe (90%)) and one real life censoring example (97%) and were inf...

Evaluation and application of summary statistic imputation to discover new height-associated loci.

As most of the heritability of complex traits is attributed to common and low frequency genetic variants, imputing them by combining genotyping chips and large sequenced reference panels is the most cost-effective approach to discover the genetic basis of these traits. Association summary statistics from genome-wide meta-analyses are available for hundreds of traits. Updating these to ever-increasing reference panels is very cumbersome as it requires reimputation of the genetic data, rerunning the associati...

Accuracy of genotype imputation in Labrador Retrievers.

The dog is a valuable model species for the genetic analysis of complex traits, and the use of genotype imputation in dogs will be an important tool for future studies. It is of particular interest to analyse the effect of factors like single nucleotide polymorphism (SNP) density of genotyping arrays and relatedness between dogs on imputation accuracy due to the acknowledged genetic and pedigree structure of dog breeds. In this study, we simulated different genotyping strategies based on data from 1179 Labr...

Foetal ultrasound measurement imputations based on growth curves versus multiple imputation chained equation (MICE).

Ultrasound measures are valuable for epidemiologic studies of risk factors for growth restriction. Longitudinal measurements enable investigation of rates of change and identification of windows where growth is impacted more acutely. However, missing data can be problematic in these studies, limiting sample size, ability to characterise windows of vulnerability, and in some instances creating bias. We sought to compare a parametric linear mixed model (LMM) approach to multiple imputation in this setting wit...

An ancestry informative marker set which recapitulates the known fine structure of populations in South Asia.

The inference of genomic ancestry using ancestry informative markers (AIMs) can be useful for a range of studies in evolutionary genetics, biomedical research and forensic analyses. However, the determination of AIMs for highly admixed populations with complex ancestries has remained a formidable challenge. Given the immense genetic heterogeneity and unique population structure of the Indian subcontinent, here we sought to derive AIMs that would yield a cohesive and faithful understanding of South Asian gen...

The benefits of negative yet informative feedback.

We investigated whether negative feedback with information could benefit both behavioral and neural responses. Fifteen participants were scanned with functional magnetic resonance imaging (fMRI) while receiving various feedbacks in a novel perceptual task. Behavioral data showed that reaction times of task performance were faster after receiving negative informative feedback compared to negative confirmatory feedback. The fMRI analysis of the interaction contrast between feedback type (informative vs. confi...

Multivariate Global Sensitivity Analysis Based on Distance Components Decomposition.

In this article, a new set of multivariate global sensitivity indices based on distance components decomposition is proposed. The proposed sensitivity indices can be considered as an extension of the traditional variance-based sensitivity indices and the covariance decomposition-based sensitivity indices, and they have similar forms. The advantage of the proposed sensitivity indices is that they can measure the effects of an input variable on the whole probability distribution of multivariate model output w...

Accurate and adaptive imputation of summary statistics in mixed-ethnicity cohorts.

Methods based on summary statistics obtained from genome-wide association studies have gained considerable interest in genetics due to the computational cost and privacy advantages they present. Imputing missing summary statistics has therefore become a key procedure in many bioinformatics pipelines, but available solutions may rely on additional knowledge about the populations used in the original study and, as a result, may not always ensure feasibility or high accuracy of the imputation procedure.

A Bayesian framework for health economic evaluation in studies with missing data.

Health economics studies with missing data are increasingly using approaches such as multiple imputation that assume that the data are "missing at random." This assumption is often questionable, as-even given the observed data-the probability that data are missing may reflect the true, unobserved outcomes, such as the patients' true health status. In these cases, methodological guidelines recommend sensitivity analyses to recognise data may be "missing not at random" (MNAR), and call for the development of ...

A comparison of different methods to handle missing data in the context of propensity score analysis.

Propensity score analysis is a popular method to control for confounding in observational studies. A challenge in propensity methods is missing values in confounders. Several strategies for handling missing values exist, but guidance in choosing the best method is needed. In this simulation study, we compared four strategies of handling missing covariate values in propensity matching and propensity weighting. These methods include: complete case analysis, missing indicator method, multiple imputation and co...

Incentives Boost Model-Based Control Across a Range of Severity on Several Psychiatric Constructs.

Human decision making exhibits a mixture of model-based and model-free control. Recent evidence indicates that arbitration between these two modes of control ("metacontrol") is based on their relative costs and benefits. While model-based control may increase accuracy, it requires greater computational resources, so people invoke model-based control only when potential rewards exceed those of model-free control. We used a sequential decision task, while concurrently manipulating performance incentives, to a...

Individuals with recurrent ankle sprain demonstrate postural instability and neuromuscular control deficits in unaffected side.

To compare proprioception, postural stability, and neuromuscular control between patients with mechanical laxity and recurrent ankle sprain.

Shedding light on the association between repetitive negative thinking and deficits in cognitive control - A meta-analysis.

Individuals who experience recurrent negative thoughts are at elevated risk for mood and anxiety disorders. It is thus essential to understand why some individuals get stuck in recurrent negative thinking (RNT), whereas others are able to disengage eventually. Theoretical models propose that individuals high in recurrent negative thinking suffer from deficits in controlling the contents of working memory. Empirical findings, however, are inconclusive. In this meta-analysis, we synthesize findings from 94 st...

Recent progress on cell-based biosensors for analysis of food safety and quality control.

Food quality and safety has become a subject of major concern for authorities and professionals in the food supply chain. Rapid methods, particularly biosensors, have exceptional specificity and sensitivity, rapid response times, low cost, relatively compact size, and are user friendly to operate. Cell-based biosensors are portable, and provide the biological activity of the analyte suitable for an initial screening of food. In this overview, the utilization of cell-based biosensors for food safety and qual...

Considerations of multiple imputation approaches for handling missing data in clinical trials.

Missing data exist in all clinical trials and missing data issue is a very serious issue in terms of the interpretability of the trial results. There is no universally applicable solution for all missing data problems. Methods used for handling missing data issue depend on the circumstances particularly the assumptions on missing data mechanisms. In recent years, if the missing at random mechanism cannot be assumed, conservative approaches such as the control-based and returning to baseline multiple imputat...

Identifying others' informative intentions from movement kinematics.

Previous research has demonstrated that people can reliably distinguish between actions with different instrumental intentions on the basis of the kinematic signatures of these actions (Cavallo, Koul, Ansuini, Capozzi, & Becchio, 2016). It has also been demonstrated that different informative intentions result in distinct action kinematics (McEllin, Knoblich, & Sebanz, 2017). However, it is unknown whether people can discriminate between instrumental actions and actions performed with an informative intenti...

The feasibility of using low-density marker panels for genotype imputation and genomic prediction of crossbred dairy cattle of East Africa.

Cost-effective high-density (HD) genotypes of livestock species can be obtained by genotyping a proportion of the population using a HD panel and the remainder using a cheaper low-density panel, and then imputing the missing genotypes that are not directly assayed in the low-density panel. The efficacy of genotype imputation can largely be affected by the structure and history of the specific target population and it should be checked before incorporating imputation in routine genotyping practices. Here, we...

Building A Longitudinal Cohort From 9-1-1 to 1-Year Using Existing Data Sources, Probabilistic Linkage, and Multiple Imputation: A Validation Study.

To describe and validate construction of a population-based, longitudinal cohort of injured older adults from 911 call to 1-year follow-up using existing data sources, probabilistic linkage, and multiple imputation.

'Recurrent losers unite': Online forums, evidence-based activism, and pregnancy loss.

Women with recurrent pregnancy loss face unique challenges associated with the social invisibility of their condition, patchy medical knowledge about it, and often intransigent positions of doctors. We approach online forums as sites of knowledge production and examine discussions among women with recurrent miscarriages. We observe that some forum participants gather, summarize, and share experience-based and research-based information in order to challenge certain medical conceptions. We describe these eff...


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