Biostatistics Commons^™

Optimizing Tumor Xenograft Experiments Using Bayesian Linear And Nonlinear Mixed Modelling And Reinforcement Learning, Mary Lena Bleile

Statistical Science Theses and Dissertations

Tumor xenograft experiments are a popular tool of cancer biology research. In a typical such experiment, one implants a set of animals with an aliquot of the human tumor of interest, applies various treatments of interest, and observes the subsequent response. Efficient analysis of the data from these experiments is therefore of utmost importance. This dissertation proposes three methods for optimizing cancer treatment and data analysis in the tumor xenograft context. The first of these is applicable to tumor xenograft experiments in general, and the second two seek to optimize the combination of radiotherapy with immunotherapy in the tumor xenograft …

Detecting Gene-Gene Or Gene Environment Interactions In Association With Complex Disease Outcomes, Taiwo Adetunji Famuyiwa

Theses and Dissertations

Identifying gene–gene and gene–environment interaction is complicated and gainsaying most especially because of high multifactor dimensions involve in the analysis of such combination discrediting the functionality of parametric statistical method like Logistic Regression. [22] developed a multi-factor-dimensionality reduction (MDR) method for detecting and characterizing high-order gene-gene and gene-environment interactions in case-control and discordant-sib-pair studies with relatively small samples, which is inspired by the combinatorial partitioning method of [18]. [16] proposed Generalized MDR (GMDR) framework based on the score of a generalized linear model which allows adjustment of covariates, provides a unified framework for handling both dichotomous and quantitative phenotypes. However, …

Identifying Limitations In Using Diagnostic Testing For Absorption Of Passive Maternal Immunity In Neonatal Beef Calves To Predict Pre-Weaning Disease, Alexis Charlotte Thompson

Theses and Dissertations

Calves are born agammaglobulinemic and rely on colostrum consumption for the transfer of maternal passive immunity. Calves that fail to absorb adequate amounts of maternal antibodies from colostrum are commonly referred to as having failed transfer of passive immunity (FTPI). The overall aim of this dissertation was to explore the usefulness of FTPI testing in neonatal beef calves to predict their risk for subsequent illness or death. The objectives were to evaluate the impact of FTPI on pre-weaning disease in beef and dairy calves, quantify and compare the variance in IgG concentrations measured by radial immunodiffusion and serum total protein …

Drug Ideologies Of The United States, Macy Montgomery

Helm's School of Government Conference - 2021-2024

The United States has been increasingly creating lenient drug policies. Seventeen states and Washington, the District of Columbia, legalized marijuana, and Oregon decriminalized certain drugs, including methamphetamine, heroin, and cocaine. The medical community has proven that drugs, including marijuana, have myriad adverse health side effects. This leads to two questions: Why does the United States government continue to create lenient drug policies, and what reasons do citizens give for legalizing drugs when the medical community has proven them harmful? The paper hypothesizes that the disadvantages of drug legalization outweigh its benefits because of the numerous harms it causes, such as …

Observational Study Of Organisational Responses Of 17 Us Hospitals Over The First Year Of The Covid-19 Pandemic, Esther K. Choo, Matthew Strehlow, Marina Del Rios, Evrim Oral, Ruth Pobee, Andrew Nugent, Stephen C. Lim, Christian Hext, Sarah Newhall, Diana Ko, Srihari V. Chari, Amy Wilson, Joshua J. Baugh, David Callaway, Mucio Kit Delgado, Zoe Glick, Christian J. Graulty, Nicholas Hall, Abdusebur Jemal, Madhav Kc, Aditya Mahadevan, Milap Mehta, Andrew C. Meltzer, Dar'ya Pozhidayeva, Daniel Resnick-Ault

School of Public Health Faculty Publications

Objectives The COVID-19 pandemic has required significant modifications of hospital care. The objective of this study was to examine the operational approaches taken by US hospitals over time in response to the COVID-19 pandemic. Design, setting and participants This was a prospective observational study of 17 geographically diverse US hospitals from February 2020 to February 2021. Outcomes and analysis We identified 42 potential pandemic-related strategies and obtained week-to-week data about their use. We calculated descriptive statistics for use of each strategy and plotted percent uptake and weeks used. We assessed the relationship between strategy use and hospital type, geographic region …

Inter-Rater Reliability Of Statistics Based On Reconstructed Individual Patient Data From Published Kaplan-Meier Curves, Megan E. Smith

Theses & Dissertations

Introduction: Time-to-event outcomes include two elements: an indicator variable for whether the event has taken place, and the length of time from some origin point to the occurrence of the event of interest. Due to the complexity of these data, secondary analysis methods, such as indirect comparisons and meta-analysis, are easier to perform when individual-level patient data (IPD) is available.

Objectives: In 2021, an R package IPDfromKM was published, which contains an algorithm for reconstructing IPD from a Kaplan-Meier graph. The current research aimed to investigate the reproducibility of the IPDfromKM algorithm.

Methods: Three statisticians (MS, LS, …

Trends In Resources For Neonatal Intensive Care At Delivery Hospitals For Infants Born Younger Than 30 Weeks' Gestation, 2009-2020, Nansi S. Boghossian, Marco Geraci, Ciaran S. Phibbs, Scott A. Lorch, Erika M. Edwards, Jeffrey D. Horbar

Faculty Publications

Importance: In an ideal regionalized system, all infants born very preterm would be delivered at a large tertiary hospital capable of providing all necessary care. Objective: To examine whether the distribution of extremely preterm births changed between 2009 and 2020 based on neonatal intensive care resources at the delivery hospital. Design, Setting, and Participants: This retrospective cohort study was conducted at 822 Vermont Oxford Network (VON) centers in the US between 2009 and 2020. Participants included infants born at 22 to 29 weeks' gestation, delivered at or transferred to centers participating in the VON. Data were analyzed from February to …

Characterization Of Public Opinion On Severity Of Mental Illness And Hiv Based On Individual Traits Using Hierarchical Multi-Category Probit Models, Md Moinul Ahsan

Graduate Theses and Dissertations

In this thesis, we focus on modeling categorical response variables from public opinion datasets. A hierarchical probit model was used to analyze these different variables. Particularly for multinomial data, we tried different covariate settings to see the model’s performance. For that purpose, we tried two different estimation techniques. The first algorithm uses identified parameters by fixing the first diagonal element of the covariance matrix at 1. The second algorithm uses one unidentifiable parameter and subsequently identifies the parameters by fixing the trace of the covariance matrix. The results from the simulation study confirm that the trace-restricted algorithm performs better with …

Bayesian Semi-Mechanistic Dose-Finding Designs For Phase I Oncology Trials, Chao Yang

Dissertations and Theses (Open Access)

Bayesian adaptive designs are getting more popular in research and in practice because they are flexible and efficient in evaluating an experimental drug. In oncology, despite the great advances in novel dose-finding designs, the high failure rates of clinical cancer drug development from phase I to III trials call for further improvements on novel designs, in addition to the need to promote and adopt novel designs in practice. Because anticancer agents often have a narrow therapeutic index, an accurate identification of the maximum tolerated dose (MTD) in a phase I trial is crucial for identifying a tolerable and efficacious dose …

Non-Destructive Imaging Of Phytosulfokine Trafficking In Plants Using Fiber-Optic Fluorescence Microscopy, Bernard Abakah

Electronic Theses and Dissertations

Plants secrete peptide ligands and use receptor signaling to respond to stress and control development. Understanding these phenomena is key to improving plant health and productivity for food, fiber, and energy applications. Phytosulfokine (PSK), a sulfated peptide hormone, regulates plant cell division, growth, and stress tolerance via specific phytosulfokine receptors (PSKRs). This study uses fiber-optic fluorescence microscopy to elucidate trafficking of PSK in live plants. The microscope features two-color optics and an objective lens connected to a 1-m coherent imaging fiber mounted on either a conventional upright microscope body or 5-axis positioning system (X–Y–Z plus pitch and yaw). PSK and …

On Cox Proportional Hazards Model Performance Under Different Sampling Schemes, Hani Samawi, Lili Yu, Jingjing Yin

Biostatistics, Epidemiology & Environmental Health Sciences: Faculty Publications

Cox’s proportional hazards model (PH) is an acceptable model for survival data analysis. This work investigates PH models’ performance under different efficient sampling schemes for analyzing time to event data (survival data). We will compare a modified Extreme, and Double Extreme Ranked Set Sampling (ERSS, and DERSS) schemes with a simple random sampling scheme. Observations are assumed to be selected based on an easy-to-evaluate baseline available variable associated with the survival time. Through intensive simulations, we show that these modified approaches (ERSS and DERSS) provide more powerful testing procedures and more efficient estimates of hazard ratio than those based on …

Employee Attrition: Analyzing Factors Influencing Job Satisfaction Of Ibm Data Scientists, Graham Nash

Symposium of Student Scholars

Employee attrition is a relevant issue that every business employer must consider when gauging the effectiveness of their employees. Whether or not an employee chooses to leave their job can come from a multitude of factors. As a result, employers need to develop methods in which they can measure attrition by calculating the several qualities of their employees. Factors like their age, years with the company, which department they work in, their level of education, their job role, and even their marital status are all considered by employers to assist in predicting employee attrition. This project will be analyzing a …

Statistical Analysis Of The Relationship Between Protected Bird Species And National Parks, Katherine Harmon

Symposium of Student Scholars

The ecological diversity of Earth is majorly threatened by habitat loss due to the destruction by human intervention. The conservation status of all identified species are classified into nine categories of varying vulnerability as described by the International Union for Conservation of Nature’s Red List. By understanding the vulnerability of specific species, scientists can work to maintain a viable and healthy ecosystem globally by instilling rules and regulations of observed habitats for threatened species. These habitats are identified by surveying potential locations for threatened species and determining the population size at each site. An example of one of these surveys …

A Pharmacoepidemiological Study Of Myocarditis And Pericarditis Following The First Dose Of Mrna Covid-19 Vaccine In Europe, Joana Tome, Logan Cowan, Isaac Fung

Biostatistics, Epidemiology & Environmental Health Sciences: Faculty Publications

This study assessed the myocarditis and pericarditis reporting rate of the first dose of mRNA COVID-19 vaccines in Europe. Myocarditis and pericarditis data pertinent to mRNA COVID19 vaccines (1 January 2021–11 February 2022) from EudraVigilance database were combined with European Centre for Disease Prevention and Control (ECDC)’s vaccination tracker data. The reporting rate was expressed as events (occurring within 28 days of the first dose) per 1 million individuals vaccinated. An observed-to-expected (OE) analysis quantified excess risk for myocarditis or pericarditis following the first mRNA COVID-19 vaccination. The reporting rate of myocarditis per 1 million individuals vaccinated was 17.27 (95% …

Knowledge, Attitude, And Behavioral Intention About Oral Cancer Among Public Health Students In Southeast Georgia, Ravneet Kaur, Gulzar H. Shah

Biostatistics, Epidemiology & Environmental Health Sciences: Faculty Publications

Background: Oral cancer (OC) is a significant public health problem; however, the degree to which the future public health workforce is aware of this issue is not well researched. The purpose of this study is to explore the level of knowledge, attitudes, and behavioral intentions about OC among public health students.
Materials and Methods: A sequential exploratory mixed-method research design was employed for this study. Using quantitative and qualitative measures, a survey was administered to 129 public health students. Subsequently, to understand the quantitative findings, two follow-up focus groups were conducted with survey participants.
Results: We found …

Survival Models With Background Mortality, Shujie Chen

Theses and Dissertations

In this dissertation, we focus on studying three mixture cure models with background mortality. With the development of treatment, patients may be cured and suffer from other cause of death. The cure model with background mortality can measure the population cure which refers to the patients with comparable mortality with their counterpart in general population. Three types of survival models are investigated, including generalized odds rate (GOR) model, cure model with background mortality for right censoring and interval censoring, and extended illness death model via incorporating “cure” fraction. All methods are validated via comprehensive simulation studies and real data application. …

Prevalence Of Sars-Cov-2 Antibodies In Liberty University Student Population, Emily Bonus

Senior Honors Theses

In 2020, the virus SARS-CoV-2 gained attention as it spread around the world. Its antibodies are poorly understood, and little research focuses on those with few COVID-19 complications yet large numbers of close contacts: university students. This longitudinal study recorded SARS-CoV-2 antibody presence in 107 undergraduate Liberty University students twice during early 2021. After extensive data cleaning and the application of various statistical tests and ANOVAs, the data seems to show that in the case of COVID-19 infections, SARS-CoV-2 IgM antibodies are immediately produced, and then IgG antibodies follow later. However, the COVID-19 vaccine causes the production of both IgM …

Community Participation And Perspectives Of Ambondrolava Mangrove Restoration Project, Nadine Shannon

Independent Study Project (ISP) Collection

Madagascar’s mangrove forests are intertidal ecosystems that provide numerous valuable ecosystem services but are nonetheless under pressure from large amounts of deforestation. On the southwestern coast of Madagascar, the village of Ambondrolava practices community led management of the mangrove and its resources. This research project studied the evolution of the mangrove area using GIS data, and investigated, through interviews, the relationship between the local community of Ambondrolava and the organizations that manage the mangrove ecosystem. From 2000 to 2018, the zone of the mangrove has experienced a net loss in area every year, despite reforestation efforts. Most community members interviewed …

Detecting Spatially Varying Coefficient Effects With Conditional Autoregressive Models: A Simulation Study Using Social Determinants Of Health Screening Data, Reid J. Demass

Theses and Dissertations

Generalized linear models which include spatially varying coefficient terms allow researchers to determine if the association between predictor and outcome variables vary across geographic space. Such models are particularly applicable to research with public health data where interventions and limited health care resources must be allocated carefully. The integrated nested Laplace approximation (INLA) methodology available in the R INLA package is a popular tool to estimate spatially varying coefficients. To assess the performance of the estimation procedure, patient emergency department (ED) visits were simulated from data sourced from a pilot study at Prisma Health. The INLA technique was used to …

Sparse Partitioned Empirical Bayes Ecm Algorithms For High-Dimensional Linear Mixed Effects And Heteroscedastic Regression, Anja Zgodic

Theses and Dissertations

Variable selection methods in both the frequentist and Bayesian frameworks are powerful techniques that provide prediction and inference in high-dimensional linear regression models. These methods often assume independence between observations and normally distributed errors with the same variance. In practice, these two assumptions are often violated. To mitigate this, we develop efficient and powerful Bayesian approaches for linear mixed modeling and heteroscedastic linear regression. These method offers increased flexibility through the development of empirical Bayes estimators for hyperparameters, with computationally efficient estimation through the Expectation Conditional-Minimization (ECM) algorithm. The novelty of these approaches lies in the partitioning and parameter expansion, …

Wernicke's Encephalopathy: Mapping The Risk Factors Throughout The State Of South Carolina, Shannon M. Rychener

Senior Theses

Wernicke’s Encephalopathy is a consistently underrecognized neurodegenerative brain disorder resulting from prolonged thiamine deficiency. Clinical presentation of the disease results from brain lesions attributable to thiamine deficiency. Because these lesions occur in various locations in the cerebral cortex, symptoms can vary significantly. Varied presentation of symptoms, in addition to the lack of a widely accepted biomarker for the disorder cause challenges to clinicians when identifying and diagnosing the disorder. Due to these challenges, healthcare providers must heavily rely on patient history and risk factor prevalence when multiple symptoms of the disorder are present. By mapping the prevalence of the four …

The Effects Of Demographics And Risk Factors On The Morphological Characteristics Of Human Femoropopliteal Arteries, Sayed Ahmadreza Razian, Majid Jadidi, Alexey Kamenskiy

UNO Student Research and Creative Activity Fair

Background: Disease of the lower extremity arteries (Peripheral Arterial Disease, PAD) is associated with high morbidity and mortality. During disease development, the arteries adapt by changing their diameter, wall thickness, and residual deformations, but the effects of demographics and risk factors on this process are not clear.

Methods: Superficial femoral arteries from 736 subjects (505 male, 231 female, 12 to 99 years old, average age 51±17.8 years) and the associated demographic and risk factor variables were used to construct machine learning (ML) regression models that predicted morphological characteristics (diameter, wall thickness, and longitudinal opening angle resulting from the …

Fuzzy Kc Clustering Imputation For Missing Not At Random Data, Markku A. Malmi Jr.

USF Tampa Graduate Theses and Dissertations

Research has a variety of difficulties, especially when involving human subjects, and one of the most prevalent is the issue of missing data. Missing data will always be present in research due to the fact there is no perfect method for collecting data and protecting against human error or mechanical failure. This requires researchers to be able to mitigate the problems that come along with missing data; reduction in power of an analysis and bias introduced by the missing pattern. This research investigated a non-parametric method using a nested approach of fuzzy K-Modes and fuzzy C-Means clustering to impute missing …

Patient And Physician Factors Associated With First Diagnosis Of Non-Affective Psychotic Disorder In Primary Care, Joshua C. Wiener, Rebecca Rodrigues, Jennifer N S Reid, Suzanne Archie, Richard G Booth, Chiachen Cheng, Saadia Hameed Jan, Paul Kurdyak, Arlene G Macdougall, Lena Palaniyappan, Bridget L Ryan, Kelly K. Anderson

Epidemiology and Biostatistics Publications

Primary care physicians play a central role in pathways to care for first-episode psychosis, and their increased involvement in early detection could improve service-related outcomes. The aim of this study was to estimate the proportion of psychosis first diagnosed in primary care, and identify associated patient and physician factors. We used linked health administrative data to construct a retrospective cohort of people aged 14-35 years with a first diagnosis of non-affective psychosis in Ontario, Canada between 2005-2015. We restricted the sample to patients with help-seeking contacts for mental health reasons in primary care in the six months prior to first …

Evaluating The Feasibility And Potential Impacts Of A Recovery-Oriented Psychosocial Rehabilitation Toolkit In A Health Care Setting In Kenya: A Mixed-Methods Study, Regina Casey, Joshua C. Wiener, Terry Krupa, Rosemary Lysaght, Marlene Janzen Le Ber, Ruth Ruhara, Elizabeth Price, Romaisa Pervez, Sean Kidd, Victoria Mutiso, David M Ndetei, Arlene G Macdougall

Epidemiology and Biostatistics Publications

OBJECTIVES: This pilot study evaluated the feasibility and potential impacts of delivering the Psychosocial Rehabilitation (PSR) Toolkit for people with serious mental illness within a health care setting in Kenya.

METHOD: This study used a convergent mixed-methods design. Participants were people with serious mental illness (n = 23), each with an accompanying family member, who were outpatients of a hospital or satellite clinic in semirural Kenya. The intervention consisted of 14 weekly group sessions of PSR cofacilitated by health care professionals and peers with mental illness. Quantitative data were collected from patients and family members using validated outcome measures before …

Presidential Vote Share And Covid-19 Vaccination Rate In Indonesia: A District-Level Cross-Sectional Ecological Study, Gede Benny Setia Wirawan, Ni Luh Zallila Gustina, Ivy Cerelia Valerie, I Gusti Ayu Indah Pradnyani Rs, Muchamad Zaenal Arifin, Pande Putu Januraga

Kesmas

Political affiliation has been reported as a determinant of COVID-19 vaccine acceptance in some countries, although few studies have examined the Asian context. This study aims to fill this gap by employing an ecological study design using Indonesian regions as data points. Political affiliation was represented by incumbent President Jokowi’s vote share in the 2019 presidential election. Potential confounders included population density, human development index, availability of hospitals and primary health care, 2019–2020 economic growth, COVID-19 mortality rate, and proportion of Muslims in the population. The final analysis included 201 out of 501 districts and cities in Indonesia. Controlling for …

Oxidative Stress Levels Of Fine Particulate Matter (Pm2.5) And Urinary Glutathione Of Microbus Drivers, Purnama Sidebang, Agustin Kusumayati, Budi Haryanto

Kesmas

Urinary glutathione levels are known to be an early indicator of oxidative stress in travelers. This study analyzed the association between particulate matter (PM2.5) exposure on the road and urine glutathione levels in Jakarta’s microbus drivers. This cross-sectional study involved 96 microbuses (one of Jakarta’s public transportations) drivers of nine routes in Kampung Melayu Bus Station, Jakarta, Indonesia. An anthropometric assessment and a structured questionnaire were employed. Along with the participants driving on the road, real-time personal equipment measuring PM2.5 exposure concentrations was used. Total glutathione levels were measured using a colorimetric method. A correlation test and linear regression analysis …

Information-Motivation-Behavioral Skill In Diabetes Self-Management Using Structural Equation Modeling Analysis, Dien Kurtanty, Adang Bachtiar, Cicilya Candi, Alya Pramesti, Almira Fanny Rahmasari

Kesmas

Diabetes is the “mother” of various diseases increasing the risk of morbidity and mortality. Diabetes self-management, an effort made by patients to control blood sugar levels, is an important part of the management strategy. Therefore, this study analyzed information, motivation, and behavioral skills associated with diabetes self-management. Data were collected in the Special Capital Region of Jakarta, with 277 diabetic patients selected using a questionnaire by a systematic random sampling method. The analyzed variables were information (with indicator variables of information on physical activity, nutritional intake, drug consumption, and blood sugar monitoring); sociodemographic (age, sex, occupation, education level, and duration …

Job Satisfaction Model Of Primary Health Care Midwives Based On Indonesian Workforce Research In The Health Sector, Mieska Despitasari, Adang Bachtiar, Harimat Hendarwan, Besral Besral, Yuyun Yuniar

Kesmas

Promotive, preventive, curative, and rehabilitative efforts that are comprehensive, integrated, and sustainable are employed to enhance the health state of the global population. Within this context, however, the quality of primary health care depends on job satisfaction, which leads to the happiness of human resources in the health sector. Therefore, this study aimed to analyze and formulate a job satisfaction model among primary health care midwives in Indonesia. This study was an advanced secondary data analysis of a cross-sectional study conducted in 2017 by the National Institute of Health Research and Development, Ministry of Health of the Republic of Indonesia. …

The Effect Of Covid-19-Related Occupational Stress And Burnout In Referral Hospital Nurses, Yulastri Arif, Masyithah Fadhani

Kesmas

Nurses' continuous contribution to patient health makes them prone to occupational stress, which has been exacerbated during the COVID-19 pandemic. Occupational stress that lasts for a long time and is not resolved may cause burnout. Burnout experienced by nurses can impact patients, hospital services, and themselves. This study aimed to determine the effect of occupational stress on the incidence of nurse burnout during the COVID-19 pandemic. It used a quantitative approach with a cross-sectional design. The study sample was 235 nurses in six COVID-19 referral hospitals in West Sumatra from a proportional random sampling technique. Data were collected using a …