Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 136 for “"Count data"”.
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Semiparametric Bayesian Count Data Models
Count data models have a large number of pratical applications. However there can be several problems which prevent the use of the standard Poisson regression. We may detect individual unobserved heterogeneity, caused by missing covariates, and/or excess of zero observations in our data. Both …
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Modeling time series of count data
… of this thesis is on modeling time series of count data. We consider an extension of linear Gaussian state space models - parameter driven models in which th e mean function of a time series of observed counts {Yt} is specified bv a linear predictor modified by a 'latent process’. As in linear …
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Longitudinal analysis of platelet count data
… bleeding risks in patients with low platelet counts or dysfunctional platelets. This research explores the dynamics of platelet count levels. The primary aim is to understand when and why platelet products are failing, by investigating differences in platelet count trajectories among donor …
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Longitudinal analysis for binary and count data
Longitudinal data sets consist of repeated observations of an outcome over time, and a corresponding set of covariates for each of many subjects. In many fields, multivariate analysis-of-variance is commonly used to analyse longitudinal data. Such an analysis is appropriate when responses for each …
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Poisson regression models for interval censored count data.
… Bayesian models for interval censored Poisson counts in the presence of zero inflation and missing data. As a motivating example, we consider data arising from a Human Immunodeficiency Virus (HIV) vaccine trial featuring imprecise counts, missing data, and an abundance of values which are either …
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Extended Poisson Models for Count Data With Inflated Frequencies
<p>Count data often exhibits inflated counts for zero. There are numerous papers in the literature that show how to fit Poisson regression models that account for the zero inflation. However, in many situations the frequencies of zero and of some other value <em>k</em> tends to be higher than the …
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Variable sampling intervals for control charts using count data
… as they apply to control charts that use count data. Papers by Reynolds, Arnold, and R. Amin developed properties for charts with an underlying normal distribution. These properties are extended in this thesis to accommodate an underlying Poisson distribution.
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Semiparametric and nonparametric methods for the analysis of panel count data
Panel count data are one type of event-history data concerning recurrent events. Ideally for an event-history study, subjects should be monitored continuously, so for the events that may happen recurrently over time, the exact time of each event occurrence is recordable. Data obtained in such cases …
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Bayesian approaches to problems in diagnostic testing and underreported count data.
… extends a zero-inflated Poisson distribution accounting for underreporting into the Bayesian paradigm. We analyze this Bayesian model in multiple simulation studies. When underreporting is inaccurately estimated, model parameter estimation can be biased. Placing a prior on the reporting …
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Statistical Predictions Based on Accelerated Degradation Data and Spatial Count Data
… predictions based on various types of data from different areas. We focus on applications from reliability and spatial epidemiology. Chapter 1 gives a general introduction of statistical predictions. Chapters 2 and 3 investigate the photodegradation of an organic coating, which is …
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Modeling zero-inflated and overdispersed count data: application to in-hospital mortality data
… important in organizing hospital services. Such data often have a highly right-skewed distribution for non-zero values and possible excess zero counts. Our study aims to examine the association of serum chloride levels at different time points with hospital mortality and to model the length of …
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Count Data Models for Injury Data from the National Health Interview Survey (NHIS)
… has been widely used in analyzing injury data from the National Health Interview Survey (NHIS). However, since its dependent variable is dichotomized to be either “1” (presence of an injury incident) or “0” (absence of an injury incident), logistic regression cannot provide …
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Time series analysis of count data with an application to the incidence of cholera
… comprises a study into the application of count data time series models to weekly counts of cholera cases that have been recorded in Beira, Mozambique. The study specifically looks at two classes of time series models for count data, namely observation-driven and parameter-driven, and two …
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Spatial Poisson regression : Bayesian approach correcting for measurement error with applications.
… is another common problem that plagues count data. McBride (2006) proposed a Bayesian Poisson regression model which accounts for overdispersion in count data. We extend this model by adding parameters to accommodate the problems associated with under and over reporting in the count …
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The Censored Heterogeneous Negative Binomial Model
… is an issue common to the analysis of survival data. Survival analysis evaluates time to the occurrence of an event for each individual as its outcome measure; those individuals for whom the event does not occur prior to the end of the study are said to have censored event times. Censoring may …
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Fitting Stochastic Epidemic Models to Multiple Data Types
… stochastic epidemics models to surveillance case count data. Recently, researchers began to make use of infectious disease agent genetic data to complement statistical analyses of case count data. Such genetic analyses rely on the field of phylodynamics --- a set of population genetics tools that …
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Investigation of HPV16-related genomic alterations in cervical squamous cell carcinoma
… genomic analysis involved clinical and genomics data analysis using bioinformatics and statistical methods. The Cancer Genome Atlas Program (TCGA) resource was used to download Cervical Squamous Cell Carcinoma and Endocervical Adenocarcinoma data. Molecular differentiation was performed through …
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An Evaluation of Assignment Algorithms and Post-Processing Techniques for Travel Demand Forecast Models
… Program Technical Report 255 Highway Traffic Data for Urbanized Area Project Planning and Design (NCHRP-255), published in 1982 by the Transportation Research Board. This evaluation was accomplished by using a regional travel demand forecast model calibrated and validated for the year 1990 and …
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Modified mean and quantile regression models for citation analysis
Modeling citation counts is an important subject because of its impact on providing a fair assessment for journals, researchers, articles, universities and countries. When fitting statistical models to citation count data it frequently occurs that the number of uncited articles (0s) differs from …
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