International Journal of Biostatistics最新文献_第9页

A Theorem at the Core of Colliding Bias. 碰撞偏差的一个核心定理。

IF 1.2 4区数学

International Journal of Biostatistics Pub Date : 2017-03-31 DOI: 10.1515/ijb-2016-0055

Doron J Shahar, Eyal Shahar

引用次数: 10

Parameter Estimation of a Two-Colored Urn Model Class. 双色瓮模型类的参数估计。

IF 1.2 4区数学

International Journal of Biostatistics Pub Date : 2017-03-25 DOI: 10.1515/ijb-2016-0029

Line Chloé Le Goff, Philippe Soulier

{"title":"Parameter Estimation of a Two-Colored Urn Model Class.","authors":"Line Chloé Le Goff, Philippe Soulier","doi":"10.1515/ijb-2016-0029","DOIUrl":"https://doi.org/10.1515/ijb-2016-0029","url":null,"abstract":"Though widely used in applications, reinforced random walk on graphs have never been the subject of a valid statistical inference. We develop in this paper a statistical framework for a general two-colored urn model. The probability to draw a ball at each step depends on the number of balls of each color and on a multidimensional parameter through a function, called choice function. We introduce two estimators of the parameter: the maximum likelihood estimator and a weighted least squares estimator which is less efficient, but is closer to the calibration techniques used in the applied literature. In general, the model is an inhomogeneous Markov chain and this property makes the estimation of the parameter impossible on a single path, even if it were infinite. Therefore we assume that we observe i.i.d. experiments, each of a predetermined finite length. This is coherent with the usual experimental set-ups. We apply the statistical framework to a real life experiment: the selection of a path among pre-existing channels by an ant colony. We performed experiments, which consisted of letting ants pass through the branches of a fork. We consider the particular urn model proposed by J.-L. Deneubourg et al. in 1990 to describe this phenomenon. We simulate this model for several parameter values in order to assess the accuracy of the MLE and the WLSE. Then we estimate the parameter from the experimental data and evaluate confident regions with Bootstrap algorithms. The findings of this paper do not contradict the biological literature, but give statistical significance to the values of the parameter found therein.","PeriodicalId":49058,"journal":{"name":"International Journal of Biostatistics","volume":"13 1","pages":""},"PeriodicalIF":1.2,"publicationDate":"2017-03-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1515/ijb-2016-0029","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"35070046","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 2

A Quantitative Concordance Measure for Comparing and Combining Treatment Selection Markers. 一种比较与组合处理选择标记的定量一致性方法。

IF 1.2 4区数学

International Journal of Biostatistics Pub Date : 2017-03-25 DOI: 10.1515/ijb-2016-0064

Zhiwei Zhang, Shujie Ma, Lei Nie, Guoxing Soon

{"title":"A Quantitative Concordance Measure for Comparing and Combining Treatment Selection Markers.","authors":"Zhiwei Zhang, Shujie Ma, Lei Nie, Guoxing Soon","doi":"10.1515/ijb-2016-0064","DOIUrl":"https://doi.org/10.1515/ijb-2016-0064","url":null,"abstract":"Motivated by an HIV example, we consider how to compare and combine treatment selection markers, which are essential to the notion of precision medicine. The current literature on precision medicine is focused on evaluating and optimizing treatment regimes, which can be obtained by dichotomizing treatment selection markers. In practice, treatment decisions are based not only on efficacy but also on safety, cost and individual preference, making it difficult to choose a single cutoff value for all patients in all settings. It is therefore desirable to have a statistical framework for comparing and combining treatment selection markers without dichotomization. We provide such a framework based on a quantitative concordance measure, which quantifies the extent to which higher marker values are predictive of larger treatment effects. For a given marker, the proposed concordance measure can be estimated from clinical trial data using a U-statistic, which can incorporate auxiliary covariate information through an augmentation term. For combining multiple markers, we propose to maximize the estimated concordance measure among a specified family of combination markers. A cross-validation procedure can be used to remove any re-substitution bias in assessing the quality of an optimized combination marker. The proposed methodology is applied to the HIV example and evaluated in simulation studies.","PeriodicalId":49058,"journal":{"name":"International Journal of Biostatistics","volume":"13 1","pages":""},"PeriodicalIF":1.2,"publicationDate":"2017-03-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1515/ijb-2016-0064","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"34856662","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 3

On the Conditional Power in Survival Time Analysis Considering Cure Fractions. 考虑治愈分数的生存时间分析中的条件幂。

IF 1.2 4区数学

International Journal of Biostatistics Pub Date : 2017-03-17 DOI: 10.1515/ijb-2015-0073

Andreas Kuehnapfel, Fabian Schwarzenberger, Markus Scholz

引用次数: 1

Multi-locus Test and Correction for Confounding Effects in Genome-Wide Association Studies. 全基因组关联研究中混杂效应的多位点检验和校正。

IF 1.2 4区数学

International Journal of Biostatistics Pub Date : 2016-11-01 DOI: 10.1515/ijb-2015-0091

Donglai Chen, Chuanhai Liu, Jun Xie

{"title":"Multi-locus Test and Correction for Confounding Effects in Genome-Wide Association Studies.","authors":"Donglai Chen, Chuanhai Liu, Jun Xie","doi":"10.1515/ijb-2015-0091","DOIUrl":"https://doi.org/10.1515/ijb-2015-0091","url":null,"abstract":"Genome-wide association studies (GWAS) examine a large number of genetic variants, e. g., single nucleotide polymorphisms (SNP), and associate them with a disease of interest. Traditional statistical methods for GWASs can produce spurious associations, due to limited information from individual SNPs and confounding effects. This paper develops two statistical methods to enhance data analysis of GWASs. The first is a multiple-SNP association test, which is a weighted chi-square test derived for big contingency tables. The test assesses combinatorial effects of multiple SNPs and improves conventional methods of single SNP analysis. The second is a method that corrects for confounding effects, which may come from population stratification as well as other ambiguous (unknown) factors. The proposed method identifies a latent confounding factor, using a profile of whole genome SNPs, and eliminates confounding effects through matching or stratified statistical analysis. Simulations and a GWAS of rheumatoid arthritis demonstrate that the proposed methods dramatically remove the number of significant tests, or false positives, and outperforms other available methods.","PeriodicalId":49058,"journal":{"name":"International Journal of Biostatistics","volume":"12 2","pages":""},"PeriodicalIF":1.2,"publicationDate":"2016-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1515/ijb-2015-0091","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"34587803","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 4

Mendelian Randomization using Public Data from Genetic Consortia. 孟德尔随机化使用遗传协会的公共数据。

IF 1.2 4区数学

International Journal of Biostatistics Pub Date : 2016-11-01 DOI: 10.1515/ijb-2015-0074

John R Thompson, Cosetta Minelli, Fabiola Del Greco M

{"title":"Mendelian Randomization using Public Data from Genetic Consortia.","authors":"John R Thompson, Cosetta Minelli, Fabiola Del Greco M","doi":"10.1515/ijb-2015-0074","DOIUrl":"https://doi.org/10.1515/ijb-2015-0074","url":null,"abstract":"Mendelian randomization (MR) is a technique that seeks to establish causation between an exposure and an outcome using observational data. It is an instrumental variable analysis in which genetic variants are used as the instruments. Many consortia have meta-analysed genome-wide associations between variants and specific traits and made their results publicly available. Using such data, it is possible to derive genetic risk scores for one trait and to deduce the association of that same risk score with a second trait. The properties of this approach are investigated by simulation and by evaluating the potentially causal effect of birth weight on adult glucose level. In such analyses, it is important to decide whether one is interested in the risk score based on a set of estimated regression coefficients or the score based on the true underlying coefficients. MR is primarily concerned with the latter. Methods designed for the former question will under-estimate the variance if used for MR. This variance can be corrected but it needs to be done with care to avoid introducing bias. MR based on public data sources is useful and easy to perform, but care must be taken to avoid false precision or bias.","PeriodicalId":49058,"journal":{"name":"International Journal of Biostatistics","volume":"12 2","pages":""},"PeriodicalIF":1.2,"publicationDate":"2016-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1515/ijb-2015-0074","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"34414486","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 54

Semiparametric Regression Estimation for Recurrent Event Data with Errors in Covariates under Informative Censoring. 信息过滤下协变量有误差的重复事件数据半参数回归估计。

IF 1.2 4区数学

International Journal of Biostatistics Pub Date : 2016-11-01 DOI: 10.1515/ijb-2016-0001

Hsiang Yu, Yu-Jen Cheng, Ching-Yun Wang

{"title":"Semiparametric Regression Estimation for Recurrent Event Data with Errors in Covariates under Informative Censoring.","authors":"Hsiang Yu, Yu-Jen Cheng, Ching-Yun Wang","doi":"10.1515/ijb-2016-0001","DOIUrl":"https://doi.org/10.1515/ijb-2016-0001","url":null,"abstract":"Recurrent event data arise frequently in many longitudinal follow-up studies. Hence, evaluating covariate effects on the rates of occurrence of such events is commonly of interest. Examples include repeated hospitalizations, recurrent infections of HIV, and tumor recurrences. In this article, we consider semiparametric regression methods for the occurrence rate function of recurrent events when the covariates may be measured with errors. In contrast to the existing works, in our case the conventional assumption of independent censoring is violated since the recurrent event process is interrupted by some correlated events, which is called informative drop-out. Further, some covariates may be measured with errors. To accommodate for both informative censoring and measurement error, the occurrence of recurrent events is modelled through an unspecified frailty distribution and accompanied with a classical measurement error model. We propose two corrected approaches based on different ideas, and we show that they are numerically identical when estimating the regression parameters. The asymptotic properties of the proposed estimators are established, and the finite sample performance is examined via simulations. The proposed methods are applied to the Nutritional Prevention of Cancer trial for assessing the effect of the plasma selenium treatment on the recurrence of squamous cell carcinoma.","PeriodicalId":49058,"journal":{"name":"International Journal of Biostatistics","volume":"12 2","pages":""},"PeriodicalIF":1.2,"publicationDate":"2016-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1515/ijb-2016-0001","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"34640798","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 4

The Orthogonally Partitioned EM Algorithm: Extending the EM Algorithm for Algorithmic Stability and Bias Correction Due to Imperfect Data. 正交分割EM算法:扩展EM算法的算法稳定性和不完全数据偏差校正。

IF 1.2 4区数学

International Journal of Biostatistics Pub Date : 2016-05-01 DOI: 10.1515/ijb-2015-0016

Michael D Regier, Erica E M Moodie

{"title":"The Orthogonally Partitioned EM Algorithm: Extending the EM Algorithm for Algorithmic Stability and Bias Correction Due to Imperfect Data.","authors":"Michael D Regier, Erica E M Moodie","doi":"10.1515/ijb-2015-0016","DOIUrl":"https://doi.org/10.1515/ijb-2015-0016","url":null,"abstract":"We propose an extension of the EM algorithm that exploits the common assumption of unique parameterization, corrects for biases due to missing data and measurement error, converges for the specified model when standard implementation of the EM algorithm has a low probability of convergence, and reduces a potentially complex algorithm into a sequence of smaller, simpler, self-contained EM algorithms. We use the theory surrounding the EM algorithm to derive the theoretical results of our proposal, showing that an optimal solution over the parameter space is obtained. A simulation study is used to explore the finite sample properties of the proposed extension when there is missing data and measurement error. We observe that partitioning the EM algorithm into simpler steps may provide better bias reduction in the estimation of model parameters. The ability to breakdown a complicated problem in to a series of simpler, more accessible problems will permit a broader implementation of the EM algorithm, permit the use of software packages that now implement and/or automate the EM algorithm, and make the EM algorithm more accessible to a wider and more general audience.","PeriodicalId":49058,"journal":{"name":"International Journal of Biostatistics","volume":"12 1","pages":"65-77"},"PeriodicalIF":1.2,"publicationDate":"2016-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1515/ijb-2015-0016","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"34427725","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Evaluations of the Optimal Discovery Procedure for Multiple Testing. 多重测试最优发现过程的评价。

IF 1.2 4区数学

International Journal of Biostatistics Pub Date : 2016-05-01 DOI: 10.1515/ijb-2015-0027

Daniel B Rubin

{"title":"Evaluations of the Optimal Discovery Procedure for Multiple Testing.","authors":"Daniel B Rubin","doi":"10.1515/ijb-2015-0027","DOIUrl":"https://doi.org/10.1515/ijb-2015-0027","url":null,"abstract":"The Optimal Discovery Procedure (ODP) is a method for simultaneous hypothesis testing that attempts to gain power relative to more standard techniques by exploiting multivariate structure [1]. Specializing to the example of testing whether components of a Gaussian mean vector are zero, we compare the power of the ODP to a Bonferroni-style method and to the Benjamini-Hochberg method when the testing procedures aim to respectively control certain Type I error rate measures, such as the expected number of false positives or the false discovery rate. We show through theoretical results, numerical comparisons, and two microarray examples that when the rejection regions for the ODP test statistics are chosen such that the procedure is guaranteed to uniformly control a Type I error rate measure, the technique is generally less powerful than competing methods. We contrast and explain these results in light of previously proven optimality theory for the ODP. We also compare the ordering given by the ODP test statistics to the standard rankings based on sorting univariate p-values from smallest to largest. In the cases we considered the standard ordering was superior, and ODP rankings were adversely impacted by correlation.","PeriodicalId":49058,"journal":{"name":"International Journal of Biostatistics","volume":"12 1","pages":"21-9"},"PeriodicalIF":1.2,"publicationDate":"2016-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1515/ijb-2015-0027","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"34427723","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 5

AUC-Maximizing Ensembles through Metalearning. auc -通过元学习最大化集成。

IF 1.2 4区数学

International Journal of Biostatistics Pub Date : 2016-05-01 DOI: 10.1515/ijb-2015-0035

Erin LeDell, Mark J van der Laan, Maya Petersen

引用次数: 24