2,003 Hits in 2.5 sec

Clinical and MRI activity as determinants of sample size for pediatric multiple sclerosis trials

L. H. Verhey, A. Signori, D. L. Arnold, A. Bar-Or, A. D. Sadovnick, R. A. Marrie, B. Banwell, M. P. Sormani
2013 Neurology  
binomial time to event; TTFR 5 time to first relapse; ZINB 5 zero-inflated negative binomial; ZIP 5 zero-inflated Poisson.  ...  Methods: Poisson and negative binomial models were fit to new T2 lesion and relapse count data, and negative binomial time-to-event and exponential models were fit to TTFR data of 42 children with MS enrolled  ...  , iii) the zero-inflated Poisson (ZIP) model, and iv) the zero-inflated NB (ZINB) model.  ... 
doi:10.1212/wnl.0b013e3182a6cb9b pmid:23966255 pmcid:PMC3795606 fatcat:7x2tir5awrcdnhczpetlkokaoq

Migraine day frequency in migraine prevention: longitudinal modelling approaches

Gian Luca Di Tanna, Joshua K. Porter, Richard B. Lipton, Alan Brennan, Stephen Palmer, Anthony J. Hatswell, Sandhya Sapra, Guillermo Villa
2019 BMC Medical Research Methodology  
Using these cohort-level endpoints in economic models, accounting for variation among patients is challenging.  ...  Health economic models are critical tools to inform reimbursement agencies on health care interventions.  ...  Placebo modelling data: MMDs of the EM study (a) and the CM study (b) negative binomial regression, beta binomial regression and zero-inflated negative binomial regression.  ... 
doi:10.1186/s12874-019-0664-5 pmid:30674285 pmcid:PMC6343253 fatcat:cnjxazdvgngwzml5ueu75rltgi

Zero adjusted models with applications to analysing helminths count data

Michael G Chipeta, Bagrey M Ngwira, Christopher Simoonga, Lawrence N Kazembe
2014 BMC Research Notes  
The choice between the hurdle and zero-inflated models should be based on the aim and endpoints of the study.  ...  Count data models including traditional (Poisson and negative binomial) models, zero modified models (zero inflated Poisson and zero inflated negative binomial) and hurdle models (Poisson logit hurdle  ...  For example, if the study design leads to count endpoints with both structural and sample zeros then generally the zero-inflated modeling framework is more appropriate, while in contrast, if the endpoint  ... 
doi:10.1186/1756-0500-7-856 pmid:25430726 pmcid:PMC4289350 fatcat:gyirfxk25farln7yt5havexajq

Ecotoxicology is not normal

Eduard Szöcs, Ralf B. Schäfer
2015 Environmental science and pollution research international  
tions from counts by binomial GLMs. These methods should become standard in ecotoxicology.  ...  Methods to deal with overdispersed binomial data are for example quasi methods (see above) or Generalized Linear Mixed models (GLMM).  ...  Simulations Count data For detecting a general treatment effect, GLM nb and GLM p showed inflated Type I error rates, whereas KW was conservative at low sample sizes.  ... 
doi:10.1007/s11356-015-4579-3 pmid:25953608 fatcat:ckcpw7ejyzdfdmtllnvnaiolfe

Bayesian model selection techniques as decision support for shaping a statistical analysis plan of a clinical trial: An example from a vertigo phase III study with longitudinal count data as primary endpoint

Christine Adrion, Ulrich Mansmann
2012 BMC Medical Research Methodology  
In particular, trials with longitudinal count data as primary endpoints pose challenges for model choice and model validation.  ...  Methods: We focus on generalized linear mixed models (GLMMs) for the analysis of longitudinal count data. A series of distributions with over-and under-dispersion is considered.  ...  Variability of mean logarithmic score LS (r) for true negative binomial (NB) compared with arcsinh, (zero-inflated) Poisson and zero-inflated NB model (r = 1, . . . , 100 iterations per scenario).  ... 
doi:10.1186/1471-2288-12-137 pmid:22962944 pmcid:PMC3554595 fatcat:htvioxhcibefba6ogi6af3nf2e

Group sequential designs for negative binomial outcomes

Tobias Mütze, Ekkehard Glimm, Heinz Schmidli, Tim Friede
2018 Statistical Methods in Medical Research  
by negative binomial distributions.  ...  , the number of relapses in multiple sclerosis, the number of hospitalizations in heart failure, and the number of exacerbations in asthma or in chronic obstructive pulmonary disease (COPD) are often modeled  ...  In this manuscript we focus on group sequential designs with recurrent events modeled by a negative binomial distribution which is commonly considered to model endpoints in clinical trials in multiple  ... 
doi:10.1177/0962280218773115 pmid:29770729 fatcat:5c4zg2a27zhnlhfpnd7vpuxtli

Performance of Some Correlation Coefficients When Applied to Zero-Clustered Data

L. W. Huson
2007 Journal of Modern Applied Statistical Methods  
Methodology I Generating Samples of Correlated Zero-Clustered Data Two different models were used to generate zero-clustered data for the simulation study -the binomial-lognormal model and the truncated  ...  simulation study of the performance of the Pearson and Spearman correlation coefficients, when applied to zero-clustered data generated using the binomial-lognormal model. -------------------- -------  ... 
doi:10.22237/jmasm/1193890560 fatcat:xhdzyfoanvfvja5xi6bejaeiam

Analysis of peginterferon β-1a exposure and Gd-enhanced lesion or T2 lesion response in relapsing-remitting multiple sclerosis patients

Yaming Hang, Xiao Hu, Jie Zhang, Shifang Liu, Aaron Deykin, Ivan Nestorov
2016 Journal of Pharmacokinetics and Pharmacodynamics  
Several longitudinal count models, including marginal, mixed effect, and mixture models, were compared to explore the relationship between AUC ss and Gd? lesion count (or T2 lesion count).  ...  Steady state 4-week AUC (AUCss) was derived for each individual based on sparse pharmacokinetic (PK) sample and a population PK model.  ...  lesion count over 48 months in nine MS patients; these models incorporated different distribution families (Poisson, ZIP, generalized Poisson, negative binomial, and zero-inflated negative binomial) with  ... 
doi:10.1007/s10928-016-9477-x pmid:27299457 pmcid:PMC4954841 fatcat:rzlpvwuqlvffxog2zaygecax5i

Bayesian Gamma-Negative Binomial Modeling of Single-Cell RNA Sequencing Data [article]

Siamak Zamani Dadaneh, Paul de Figueiredo, Sing-Hoi Sze, Mingyuan Zhou, Xiaoning Qian
2019 arXiv   pre-print
Results: In this paper, we propose a fully generative hierarchical gamma-negative binomial (hGNB) model of scRNA-seq data, obviating the need for explicitly modeling zero inflation.  ...  The unique analytic challenge is to appropriately model highly over-dispersed scRNA-seq count data with prevalent dropouts (zero counts), making zero-inflated dimensionality reduction techniques popular  ...  Zeroinflated negative binomial-based wanted variation extraction (ZINB-WaVE) [9] directly models the scRNAseq counts using a zero-inflated negative binomial distribution, while accounting for both gene-and  ... 
arXiv:1908.00650v1 fatcat:mj7cwzekizdo3meguy3quyqzuu

A statistical simulation model for field testing of non-target organisms in environmental risk assessment of genetically modified plants

Paul W. Goedhart, Hilko van der Voet, Ferdinando Baldacchino, Salvatore Arpaia
2014 Ecology and Evolution  
The simulation model, available as Supplementary Material, can be used to generate count data having different statistical distributions possibly with excess-zeros.  ...  This paper describes a general framework for simulating data typically encountered in environmental risk assessment of genetically modified plants.  ...  The simulation model described in this paper can be used to generate data for various endpoints having Figure 6 .  ... 
doi:10.1002/ece3.1019 pmid:24834325 pmcid:PMC4020688 fatcat:psf7et6f3vdf7imktyoq7xsrdi

Meta analysis of binary data with excessive zeros in two-arm trials

Saman Muthukumarana, David Martell, Ram Tiwari
2019 Journal of Statistical Distributions and Applications  
A zero inflated binomial model with excessive zero parameters were used to account for excessive zeros in treatment and control arms.  ...  Results from the data analysis and the model selection also indicate that the proposed Bayesian method, while accounting for zero events, adjusts for excessive zeros and provides better fit to the data  ...  Also note that Binomial and zero inflated Binomial models identify more heterogeneous study effects than DerSimonian-Laird random effects model.  ... 
doi:10.1186/s40488-019-0099-x fatcat:l3ke5jo6kncepoqx5s5lx2o37q

An integrated model for detecting significant chromatin interactions from high-resolution Hi-C data

Mark Carty, Lee Zamparo, Merve Sahin, Alvaro González, Raphael Pelossof, Olivier Elemento, Christina S. Leslie
2017 Nature Communications  
model zero inflation and overdispersion.  ...  HiC-DC uses hurdle negative binomial regression account for systematic sources of variation in Hi-C read counts-for example, distance-dependent random polymer ligation and GC content and mappability bias-and  ...  This model is sometimes called a hurdle negative binomial model.  ... 
doi:10.1038/ncomms15454 pmid:28513628 pmcid:PMC5442359 fatcat:kyesvtqxrza3leckhzo5npbvaq

Bayesian gamma-negative binomial modeling of single-cell RNA sequencing data

Siamak Zamani Dadaneh, Paul de Figueiredo, Sing-Hoi Sze, Mingyuan Zhou, Xiaoning Qian
2020 BMC Genomics  
In this paper, we propose a fully generative hierarchical gamma-negative binomial (hGNB) model of scRNA-seq data, obviating the need for explicitly modeling zero inflation.  ...  The unique analytic challenge is to appropriately model highly over-dispersed scRNA-seq count data with prevalent dropouts (zero counts), making zero-inflated dimensionality reduction techniques popular  ...  Zero-inflated negative binomialbased wanted variation extraction (ZINB-WaVE) [9] directly models the scRNA-seq counts using a zeroinflated negative binomial distribution, while accounting for both gene-and  ... 
doi:10.1186/s12864-020-06938-8 pmid:32900358 pmcid:PMC7487589 fatcat:o2yi4lromvabhnjalal5zrllde

Peritraumatic tonic immobility is associated with PTSD symptom severity in Brazilian police officers: a prospective study

Deborah B. Maia, Augusta Nóbrega, Carla Marques-Portella, Mauro V. Mendlowicz, Eliane Volchan, Evandro S. Coutinho, Ivan Figueira
2014 Revista Brasileira de Psiquiatria  
Results: Employing a zero-inflated negative binomial regression model, we found that each additional point in the TIS was associated with a 9% increment in PCL-C mean scores (RM = 1.09), whereas for PRS  ...  Figure 3 3 Fitting for Poisson (PRN), negative binomial (NBRM), zero-inflated Poisson (ZIP), and zero-inflated negative binomial (ZINB) regression models.  ...  zero-inflated Poisson (ZIP), and zero-inflated negative binomial (ZINB). 29 The ZINB model was chosen because the proportion of cases with no symptoms in the PCL scale was excessive and data were overdispersed  ... 
doi:10.1590/1516-4446-2013-1267 pmid:25466958 fatcat:dwjmeckscfgf5fkbh4kckkpguq

Page 7018 of Mathematical Reviews Vol. , Issue 97K [page]

1997 Mathematical Reviews  
We derive interesting and useful formulae for the binomial, Poisson, negative binomial and gamma populations.”  ...  In this paper the authors consider the most general case of additive models with bounded errors and show that every suf- ficiently regular UMVU estimator is deterministic.  ... 
« Previous Showing results 1 — 15 out of 2,003 results