Journal ArticleDOI
A solution to the problem of separation in logistic regression
Georg Heinze,Michael Schemper +1 more
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A procedure by Firth originally developed to reduce the bias of maximum likelihood estimates is shown to provide an ideal solution to separation and produces finite parameter estimates by means of penalized maximum likelihood estimation.Abstract:
The phenomenon of separation or monotone likelihood is observed in the fitting process of a logistic model if the likelihood converges while at least one parameter estimate diverges to +/- infinity. Separation primarily occurs in small samples with several unbalanced and highly predictive risk factors. A procedure by Firth originally developed to reduce the bias of maximum likelihood estimates is shown to provide an ideal solution to separation. It produces finite parameter estimates by means of penalized maximum likelihood estimation. Corresponding Wald tests and confidence intervals are available but it is shown that penalized likelihood ratio tests and profile penalized likelihood confidence intervals are often preferable. The clear advantage of the procedure over previous options of analysis is impressively demonstrated by the statistical analysis of two cancer studies.read more
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Dissertation
Diagnostic research in the absence of a gold standard
TL;DR: This thesis shows that composite reference standards can cause large biases in inferences about diagnostic test accuracy and target condition disease prevalence and suggests various approaches to improve latent class analysis by augmenting the diagnostic test data.
Journal ArticleDOI
Avoiding Furosemide Ototoxicity Associated With Single-Ventricle Repair in Young Infants.
Charlene M.T. Robertson,Charlene M.T. Robertson,Karin T. Bork,Gerda Tawfik,Gwen Y Bond,Gwen Y Bond,Leonora Hendson,Irina Dinu,Elham Khodayari Moez,I. Rebeyka,Gonzalo Garcia Guerra,Ari R. Joffe +11 more
TL;DR: A practice change to ensure slow IV administration of furosemide eliminated permanent hearing loss was needed and Centers caring for critically ill infants, particularly those with single-ventricle anatomy or hypoxia, should review their drug administration guidelines and adhere to best practice for administration of IV furoSemide.
Journal ArticleDOI
Right ventricular dysfunction in patients with COVID‐19 pneumonitis whose lungs are mechanically ventilated: a multicentre prospective cohort study
Phillip J McCall,J.M. Willder,Bethany Stanley,Claudia-Martina Messow,Johansen Allan,L. Gemmell,Alex Puxty,D. W. Strachan,Colin Berry,Ben Shelley +9 more
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Comparative Analysis of Tumor Cell Dissemination to the Sentinel Lymph Nodes and to the Bone Marrow in Patients With Nonmetastasized Colon Cancer: A Prospective Multicenter Study
Benjamin Weixler,Benjamin Weixler,Carsten T. Viehl,Rene Warschkow,Rene Warschkow,Ulrich Güller,Ulrich Güller,Michaela Ramser,Guido Sauter,Markus Zuber +9 more
TL;DR: Both SNTI and BMM are independent negative prognostic factors regarding DFS and OS, and the occurrence of both is associated with significantly worse prognosis compared with either one of them.
Posted Content
Exploring the Risks and Consequences of Elder Fraud Victimization: Evidence from the Health and Retirement Study
TL;DR: In this paper, the authors examined the demographic determinants and risk factors of reporting financial fraud victimization in the Leave Behind Questionnaires (LBQs) fielded on Health and Retirement Study (HRS) respondents over three survey waves in 2008, 2010 and 2012.
References
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Book
Regression Diagnostics: Identifying Influential Data and Sources of Collinearity
TL;DR: In this article, the authors present a method for detecting and assessing Collinearity of observations and outliers in the context of extensions to the Wikipedia corpus, based on the concept of Influential Observations.
Journal ArticleDOI
Regression Diagnostics: Identifying Influential Data and Sources of Collinearity
TL;DR: This chapter discusses Detecting Influential Observations and Outliers, a method for assessing Collinearity, and its applications in medicine and science.
Journal Article
Statistical methods in cancer research. Volume I - The analysis of case-control studies.
N. E. Breslow,N. E. Day +1 more
Journal ArticleDOI
Bias reduction of maximum likelihood estimates
TL;DR: In this paper, the first-order term is removed from the asymptotic bias of maximum likelihood estimates by a suitable modification of the score function, and the effect is to penalize the likelihood by the Jeffreys invariant prior.
Book
Modelling Survival Data in Medical Research
TL;DR: This paper discusses the design of clinical trials, use of computer software in survival analysis, and some non-parametric procedures for modelling survival data.