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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Non -fatal overdose among people who inject drugs in Tehran, Iran.
Mehdi Noroozi,Peter Higgs,Azadeh Bayani,Bahram Armoon,Ali Nazeri Astaneh,Ladan Fattah Moghaddam,Mohammad Askari +6 more
TL;DR: The results indicate that intervention and prevention initiatives seeking to reduce overdoses among PWIDs should not only be focused on the primary drug used but also the use of alcohol and poly-drug use.
Journal ArticleDOI
Effect of Implementing the Out-of-Hospital Traumatic Brain Injury Treatment Guidelines: The Excellence in Prehospital Injury Care for Children Study (EPIC4Kids).
Joshua B. Gaither,Daniel W. Spaite,Bentley J. Bobrow,Samuel M. Keim,Bruce J Barnhart,Vatsal Chikani,Duane L. Sherrill,Kurt R. Denninghoff,Terry Mullins,P. David Adelson,Amber D Rice,Chad Viscusi,Chengcheng Hu +12 more
TL;DR: Both adjusted survival to hospital admission and discharge improved in children with severe traumatic brain injury, indicating a potential severity-based interventional opportunity for guideline effectiveness.
Journal ArticleDOI
Genetic loci associated with prevalent and incident myocardial infarction and coronary heart disease in the Cohorts for Heart and Aging Research in Genomic Epidemiology (CHARGE) Consortium
Julie Hahn,Yi-Ping Fu,Michael R. Brown,Joshua C. Bis,Paul S. de Vries,Paul S. de Vries,Mary F. Feitosa,Lisa R. Yanek,Stefan Weiss,Franco Giulianini,Albert V. Smith,Xiuqing Guo,Traci M. Bartz,Diane M. Becker,Lewis C. Becker,Eric Boerwinkle,Eric Boerwinkle,Jennifer A. Brody,Yii-Der Ida Chen,Oscar H. Franco,Megan L. Grove,Tamara B. Harris,Albert Hofman,Albert Hofman,Shih-Jen Hwang,Brian G. Kral,Lenore J. Launer,Marcello Ricardo Paulista Markus,Kenneth Rice,Stephen S. Rich,Paul M. Ridker,Paul M. Ridker,Fernando Rivadeneira,Jerome I. Rotter,Nona Sotoodehnia,Kent D. Taylor,André G. Uitterlinden,André G. Uitterlinden,Uwe Völker,Henry Völzke,Jie Yao,Daniel I. Chasman,Daniel I. Chasman,Marcus Dörr,Vilmundur Gudnason,Rasika A. Mathias,Wendy S. Post,Bruce M. Psaty,Abbas Dehghan,Abbas Dehghan,Christopher J. O'Donnell,Alanna C. Morrison +51 more
TL;DR: One known locus (ANGPTL4), four new loci (PLCL1, RC3H2, TMPRSS5, and LDLRAD1) associated with cardiovascular disease risk that warrant further investigation, and no loci were significantly associated with all-cause mortality following a MI or CHD event.
Journal ArticleDOI
Preliminary investigation of the effect of treating sheep during pregnancy with a vitamin A, D, E formulation on the incidence of vaginal prolapse.
TL;DR: Administration of injectable vitamins A, D3, and E to pregnant ewes reduced the incidence of vaginal prolapse during the period from pregnancy diagnosis to set-stocking on one North Canterbury hill-country farm.
Journal ArticleDOI
Prenatal opioid-exposed infant extracellular miRNA signature obtained at birth predicts severity of neonatal opioid withdrawal syndrome
Amanda H. Mahnke,Melissa H. Roberts,Lawrence Leeman,Xingyan Ma,Ludmila N. Bakhireva,Rajesh C. Miranda +5 more
TL;DR: In this paper , extracellular microRNAs (miRNAs) in umbilical cord plasma of infants with pre-natal opioid exposure were assessed using semi-quantitative qRT-PCR arrays.
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.