Statistics and Probability Commons^™

Randomized Trial Of Interventions To Improve Childhood Asthma In Homes With Wood-Burning Stoves, Curtis W. Noonan, Erin O. Semmens, Paul Smith, Solomon W. Harrar, Luke Montrose, Emily Weiler, Marcy Mcnamara, Tony J. Ward

Statistics Faculty Publications

BACKGROUND: Household air pollution due to biomass combustion for residential heating adversely affects vulnerable populations. Randomized controlled trials to improve indoor air quality in homes of children with asthma are limited, and no such studies have been conducted in homes using wood for heating.

OBJECTIVES: Our aims were to test the hypothesis that household-level interventions, specifically improved-technology wood-burning appliances or air-filtration devices, would improve health measures, in particular Pediatric Asthma Quality of Life Questionnaire (PAQLQ) scores, relative to placebo, among children living with asthma in homes with wood-burning stoves.

METHODS: A three-arm placebo-controlled randomized trial was conducted in homes with …

Estimation Of Exposure Distribution Adjusting For Association Between Exposure Level And Detection Limit, Yuchen Yang, Brent J. Shelton, Thomas Tucker, Li Li, Richard Kryscio, Li Chen

Statistics Faculty Publications

In environmental exposure studies, it is common to observe a portion of exposure measurements to fall below experimentally determined detection limits (DLs). The reverse Kaplan–Meier estimator, which mimics the well‐known Kaplan–Meier estimator for right‐censored survival data with the scale reversed, has been recommended for estimating the exposure distribution for the data subject to DLs because it does not require any distributional assumption. However, the reverse Kaplan–Meier estimator requires the independence assumption between the exposure level and DL and can lead to biased results when this assumption is violated. We propose a kernel‐smoothed nonparametric estimator for the exposure distribution without imposing …

Selection Of Breeding Stock By U.S. Meat Goat Producers, Narayan Nyaupane, Jeffrey Gillespie, Kenneth Mcmillin, Robert Harrison, Isaac Stienei

Community & Leadership Development Faculty Publications

Using nationwide survey data, we investigate U.S. meat goat producer preferences and willingness to pay for meat goat breeding stock attributes. Discrete choice experiments were employed, and mixed logit and latent class models were used for analysis. Results showed that producers preferred animals that were highly masculine/feminine, had good structure and soundness, and were of the Boer breed, whereas they preferred fewer animals that were older, of Kiko and Spanish breeds, and priced higher. Significant preference heterogeneity was found among the respondents. Larger-scale producers had greater preference for high masculinity/femininity, good structure and soundness, and Boer bucks.

First-In-Human Clinical Trial Of Oral Onc201 In Patients With Refractory Solid Tumors, Mark N. Stein, Joseph R. Bertino, Howard L. Kaufman, Tina M. Mayer, Rebecca A. Moss, Ann W. Silk, Nancy Chan, Jyoti Malhotra, Loma Rodriguez, Joseph Aisner, Robert Aiken, Bruce G. Haffty, Robert S. Dipaola, Tracie Saunders, Andrew Zloza, Sherri Damare, Yasmeen Beckett, Bangning Yu, Saltanat Najmi, Christian Gabel, Sioghan Dickerson, Ling Zheng, Wafik S. El-Deiry, Joshua E. Allen, Martin Stogniew, Wolfgang Oster, Janice M. Mehnert

Internal Medicine Faculty Publications

Purpose: ONC201 is a small-molecule selective antagonist of the G protein–coupled receptor DRD2 that is the founding member of the imipridone class of compounds. A first-in-human phase I study of ONC201 was conducted to determine its recommended phase II dose (RP2D).

Experimental Design: This open-label study treated 10 patients during dose escalation with histologically confirmed advanced solid tumors. Patients received ONC201 orally once every 3 weeks, defined as one cycle, at doses from 125 to 625 mg using an accelerated titration design. An additional 18 patients were treated at the RP2D in an expansion phase to collect additional safety, …

Impact Of Home Visit Capacity On Genetic Association Studies Of Late-Onset Alzheimer's Disease, David W. Fardo, Laura E. Gibbons, Shubhabrata Mukherjee, M. Maria Glymour, Wayne Mccormick, Susan M. Mccurry, James D. Bowen, Eric B. Larson, Paul K. Crane

Biostatistics Faculty Publications

INTRODUCTION—Findings for genetic correlates of late-onset Alzheimer's disease (LOAD) in studies that rely solely on clinic visits may differ from those with capacity to follow participants unable to attend clinic visits.

METHODS—We evaluated previously identified LOAD-risk single nucleotide variants in the prospective Adult Changes in Thought study, comparing hazard ratios (HRs) estimated using the full data set of both in-home and clinic visits (n = 1697) to HRs estimated using only data that were obtained from clinic visits (n = 1308). Models were adjusted for age, sex, principal components to account for ancestry, and additional health indicators.

RESULTS …

Peripheral Inflammation, Apolipoprotein E4, And Amyloid-Β Interact To Induce Cognitive And Cerebrovascular Dysfunction, Felecia M. Marottoli, Yuriko Katsumata, Kevin P. Koster, Riya Thomas, David W. Fardo, Leon M. Tai

Biostatistics Faculty Publications

Cerebrovascular dysfunction is rapidly reemerging as a major process of Alzheimer’s disease (AD). It is, therefore, crucial to delineate the roles of AD risk factors in cerebrovascular dysfunction. While apolipoprotein E4 (APOE4), Amyloid-β (Aβ), and peripheral inflammation independently induce cerebrovascular damage, their collective effects remain to be elucidated. The goal of this study was to determine the interactive effect of APOE4, Aβ, and chronic repeated peripheral inflammation on cerebrovascular and cognitive dysfunction in vivo. EFAD mice are a well-characterized mouse model that express human APOE3 (E3FAD) or APOE4 (E4FAD) and overproduce human Aβ42 via expression of …

A Phase Iii, Randomized, Multi-Center, Double Blind, Placebo Controlled Study Of Safety And Efficacy Of Lofexidine For Relief Of Symptoms In Individuals Undergoing Inpatient Opioid Withdrawal, Charles W. Gorodetzky, Sharon L. Walsh, Peter R. Martin, Andrew J. Saxon, Kristen L. Gullo, Kousick Biswas

Center on Drug and Alcohol Research Faculty Publications

Background: Lofexidine is an alpha-2-adrenergic receptor agonist approved in the United Kingdom (UK) for the treatment of opioid withdrawal symptoms. Lofexidine has demonstrated better efficacy than placebo for reducing opioid withdrawal symptoms in patients undergoing opioid withdrawal with less reported hypotension than clonidine.

Methods: Designed as an FDA registration trial, this 8-day, randomized, double-blind, placebo-controlled, parallel-group study in 264 patients dependent on short-acting opioids evaluated the efficacy of lofexidine hydrochloride in reducing withdrawal symptoms in patients undergoing opioid withdrawal. The primary efficacy measures were SOWS-Gossop on Day 3 and time-to-dropout. Secondary endpoints included the proportion of participants who were completers; …

A Microrna Signature Of Response To Erlotinib Is Descriptive Of Tgfβ Behaviour In Nsclc, Madeline J. Krentz Gober, James P. Collard, Katherine L. Thompson, Esther P. Black

Pharmaceutical Sciences Faculty Publications

Our previous work identified a 13-gene miRNA signature predictive of response to the epidermal growth factor receptor (EGFR) inhibitor, erlotinib, in Non-Small Cell Lung Cancer cell lines. Bioinformatic analysis of the signature showed a functional convergence on TGFβ canonical signalling. We hypothesized that TGFβ signalling controls expression of the miRNA genes comprising an erlotinib response signature in NSCLC. Western analysis revealed that TGFβ signalling via Smad2/3/4 occurred differently between erlotinib-resistant A549 and erlotinib- sensitive PC9 cells. We showed that TGFβ induced an interaction between Smad4 and putative Smad Binding Elements in PC9. However, qRT-PCR analysis showed that endogenous miR-140/141/200c expression …

Treatment Pathway Of Bone Sarcoma In Children, Adolescents, And Young Adults, Damon R. Reed, Masanori Hayashi, Lars M. Wagner, Odion Binitie, Diana A. Steppan, Andrew S. Brohl, Eric T. Shinohara, Julia A. Bridge, David M. Loeb, Scott C. Borinstein, Michael S. Isakoff

Pediatrics Faculty Publications

When pediatric, adolescent, and young adult patients present with a bone sarcoma, treatment decisions, especially after relapse, are complex and require a multidisciplinary approach. This review presents scenarios commonly encountered in the therapy of bone sarcomas with the goal of objectively presenting a consensus, multidisciplinary management approach. Little variation was found in the authors' group with respect to local control or systemic therapy. Clinical trials were universally prioritized in all settings. Decisions regarding relapse therapies in the absence of a clinical trial had very minor variations initially, but a consensus was reached after a literature review and discussion. This review …

Risk Of Incident Clinical Diagnosis Of Alzheimer's Disease-Type Dementia Attributable To Pathology-Confirmed Vascular Disease, Hiroko H. Dodge, Jian Zhu, Randy Woltjer, Peter T. Nelson, David A. Bennett, Nigel J. Cairns, David W. Fardo, Jeffrey A. Kaye, Deniz-Erten Lyons, Nora Mattek, Julie A. Schneider, Lisa C. Silbert, Chengjie Xiong, Lei Yu, Frederick A. Schmitt, Richard J. Kryscio, Erin L. Abner, Smart Data Consortium

Sanders-Brown Center on Aging Faculty Publications

INTRODUCTION: The presence of cerebrovascular pathology may increase the risk of clinical diagnosis of Alzheimer's disease (AD).

METHODS: We examined excess risk of incident clinical diagnosis of AD (probable and possible AD) posed by the presence of lacunes and large infarcts beyond AD pathology using data from the Statistical Modeling of Aging and Risk of Transition study, a consortium of longitudinal cohort studies with more than 2000 autopsies. We created six mutually exclusive pathology patterns combining three levels of AD pathology (low, moderate, or high AD pathology) and two levels of vascular pathology (without lacunes and large infarcts or with …

Lisinopril Or Coreg Cr In Reducing Cardiotoxicity In Women With Breast Cancer Receiving Trastuzumab: A Rationale And Design Of A Randomized Clinical Trial, Maya Guglin, Pamela Munster, Angelina Fink, Jeffrey Krischer

Internal Medicine Faculty Publications

Background—Trastuzumab (TZB) is an established therapy for HER2 positive breast cancer. The use of TZB is commonly associated with cardiotoxicity manifesting as asymptomatic decrease in left ventricular ejection fraction (LVEF) or overt heart failure. Several studies demonstrated favorable effects of angiotensin converting enzyme (ACE) inhibitors and beta blockers (BB) in the prevention of chemotherapy-induced cardiotoxicity. We hypothesize that patients, randomized to receive an ACE inhibitor or a beta-blocker during trastuzumab therapy for breast cancer, will maintain a higher LVEF than patients randomized to placebo.

Methods and Results—We designed a prospective, multicenter, randomized, phase II placebo-controlled clinical trial to …

Estimated Probability Of Becoming A Case Of Drug Dependence In Relation To Duration Of Drug-Taking Experience: A Functional Analysis Approach, Olga A. Vsevolozhskaya, James C. Anthony

Biostatistics Faculty Publications

Measured as elapsed time from first use to dependence syndrome onset, the estimated "induction interval" for cocaine is thought to be short relative to the cannabis interval, but little is known about risk of becoming dependent during first months after onset of use. Virtually all published estimates for this facet of drug dependence epidemiology are from life histories elicited years after first use. To improve estimation, we turn to new month-wise data from nationally representative samples of newly incident drug users identified via probability sampling and confidential computer-assisted self-interviews for the United States National Surveys on Drug Use and Health, …

Phase Iii Prospective Randomized Comparison Trial Of Depot Octreotide Plus Interferon Alfa-2b Versus Depot Octreotide Plus Bevacizumab In Patients With Advanced Carcinoid Tumors: Swog S0518, James C. Yao, Katherine A. Guthrie, Cesar Moran, Jonathan R. Strosberg, Matthew H. Kulke, Jennifer A. Chan, Noelle Loconte, Robert R. Mcwilliams, Edward M. Wolin, Bassam Mattar, Shannon Mcdonough, Helen Chen, Charles D. Blanke, Howard S. Hochster

Markey Cancer Center Faculty Publications

Purpose

Treatment options for neuroendocrine tumors (NETs) remain limited. This trial assessed the progression-free survival (PFS) of bevacizumab or interferon alfa-2b (IFN-α-2b) added to octreotide among patients with advanced NETs.

Patients and Methods

Southwest Oncology Group (SWOG) S0518, a phase III study conducted in a US cooperative group system, enrolled patients with advanced grades 1 and 2 NETs with progressive disease or other poor prognostic features. Patients were randomly assigned to treatment with octreotide LAR 20 mg every 21 days with either bevacizumab 15 mg/kg every 21 days or 5 million units of IFN-α-2b three times per week. The primary …

Demographics, Patterns Of Care, And Survival In Pediatric Medulloblastoma, Emily V. Dressler, Therese A. Dolecek, Meng Liu, John L. Villano

Internal Medicine Faculty Publications

We evaluated the American College of Surgeon’s National Cancer Data Base (NCDB) to describe current hospital-based epidemiologic frequency, survival, and patterns of care of pediatric medulloblastoma. We analyzed NCDB 1998–2011 data on medulloblastoma for children ages 0–19 years using logistic and poisson regression, Kaplan–Meier survival estimates, and Cox proportional hazards models. 3647 cases of medulloblastoma in those aged 0–19 years were identified. Chemotherapy was received by 79 and 74% received radiation, with 65% receiving both therapies. Those who received radiation were more likely to be older than four, while those who received chemotherapy were more likely to be age four …

Tuberculosis And Risk Of Acute Myocardial Infarction: A Propensity Score-Matched Analysis, Moises A. Huaman, Richard J. Kryscio, Carl J. Fichtenbaum, David Henson, Elizabeth G. Salt, Timothy R. Sterling, Beth A. Garvy

Biostatistics Faculty Publications

Several pathogens have been associated with increased cardiovascular disease (CVD) risk. Whether this occurs with Mycobacterium tuberculosis infection is unclear. We assessed if tuberculosis disease increased the risk of acute myocardial infarction (AMI). We identified patients with tuberculosis index claims from a large de-identified database of ~15 million adults enrolled in a U.S. commercial insurance policy between 2008 and 2010. Tuberculosis patients were 1:1 matched to patients without tuberculosis claims using propensity scores. We compared the occurrence of index AMI claims between the tuberculosis and non-tuberculosis cohorts using Kaplan–Meier curves and Cox Proportional Hazard models. Data on 2026 patients with …

Functional Human Grin2b Promoter Polymorphism And Variation Of Mental Processing Speed In Older Adults, Yang Jiang, Ming Kuan Lin, Gregory A. Jicha, Xiuhua Ding, Sabrina L. Mcilwrath, David W. Fardo, Lucas S. Broster, Frederick A. Schmitt, Richard J. Kryscio, Robert H. Lipsky

Behavioral Science Faculty Publications

We investigated the role of a single nucleotide polymorphism rs3764030 (G > A) within the human GRIN2B promoter in mental processing speed in healthy, cognitively intact, older adults. In vitro DNA-binding and reporter gene assays of different allele combinations in transfected cells showed that the A allele was a gain-of-function variant associated with increasing GRIN2B mRNA levels. We tested the hypothesis that individuals with A allele will have better memory performance (i.e. faster reaction times) in older age. Twenty-eight older adults (ages 65-86) from a well-characterized longitudinal cohort were recruited and performed a modified delayed match-to-sample task. The rs3764030 polymorphism was …

High-Dimensional Repeated Measures, Martin Happ, Solomon W. Harrar, Arne C. Bathke

Statistics Faculty Publications

Recently, new tests for main and simple treatment effects, time effects, and treatment by time interactions in possibly high-dimensional multigroup repeated-measures designs with unequal covariance matrices have been proposed. Technical details for using more than one between-subject and more than one within-subject factor are presented in this article. Furthermore, application to electroencephalography (EEG) data of a neurological study with two whole-plot factors (diagnosis and sex) and two subplot factors (variable and region) is shown with the R package HRM (high-dimensional repeated measures).

Identification Of Prognostic Genes And Gene Sets For Early-Stage Non-Small Cell Lung Cancer Using Bi-Level Selection Methods, Suyan Tian, Chi Wang, Howard H. Chang, Jianguo Sun

Biostatistics Faculty Publications

In contrast to feature selection and gene set analysis, bi-level selection is a process of selecting not only important gene sets but also important genes within those gene sets. Depending on the order of selections, a bi-level selection method can be classified into three categories – forward selection, which first selects relevant gene sets followed by the selection of relevant individual genes; backward selection which takes the reversed order; and simultaneous selection, which performs the two tasks simultaneously usually with the aids of a penalized regression model. To test the existence of subtype-specific prognostic genes for non-small cell lung cancer …

Outcomes After Diagnosis Of Mild Cognitive Impairment In A Large Autopsy Series, Erin L. Abner, Richard J. Kryscio, Frederick A. Schmitt, David W. Fardo, Daniela C. Moga, Eseosa T. Ighodaro, Gregory A. Jicha, Lei Yu, Hiroko H. Dodge, Chengjie Xiong, Randall L. Woltjer, Julie A. Schneider, Nigel J. Cairns, David A. Bennett, Peter T. Nelson

Epidemiology and Environmental Health Faculty Publications

OBJECTIVE: To determine clinical and neuropathological outcomes following a clinical diagnosis of mild cognitive impairment (MCI).

METHODS: Data were drawn from a large autopsy series (N = 1,337) of individuals followed longitudinally from normal or MCI status to death, derived from 4 Alzheimer Disease (AD) Centers in the United States.

RESULTS: Mean follow‐up was 7.9 years. Of the 874 individuals ever diagnosed with MCI, final clinical diagnoses were varied: 39.2% died with an MCI diagnosis, 46.8% with a dementia diagnosis, and 13.9% with a diagnosis of intact cognition. The latter group had pathological features resembling those with a final clinical …

Intraindividual Variability In Cortisol: Approaches, Illustrations, And Recommendations, Suzanne C. Segerstrom, Sandra E. Sephton, Philip M. Westgate

Psychology Faculty Publications

Most of the variance in diurnal cortisol is attributable to intraindividual variability (IIV), defined as relatively short-term, reversible changes. Multiple methods for measuring IIV have been proposed, and some have already been applied to cortisol IIV. In the present review, measurement methods are described and applied to simulated cortisol data with known underlying differences in IIV and to real cortisol data from first-year law students. More slope variance and more residual or net variance were well captured by their individual standard deviations. Explorations of reliability suggested that 10 slopes and 50 residuals result in reliable and stable estimates of the …

Level Of Patient-Physician Agreement In Assessment Of Change Following Conservative Rehabilitation For Shoulder Pain, Stephanie D. Moore-Reed, W. Ben Kibler, Heather M. Bush, Timothy L. Uhl

Biostatistics Faculty Publications

Background Assessment of health-related status has been shown to vary between patients and physicians, although the degree of patient–physician discordance in the assessment of the change in status is unknown.

Methods Ninety-nine patients with shoulder dysfunction underwent a standardized physician examination and completed several self-reported questionnaires. All patients were prescribed the same physical therapy intervention. Six weeks later, the patients returned to the physician, when self-report questionnaires were re-assessed and the Global Rating of Change (GROC) was completed by the patient. The physician completed the GROC retrospectively. To determine agreement between patient and physician, intra-class correlation (ICC) coefficient and Pearson’s …

Polymer Micelle Formulation For The Proteasome Inhibitor Drug Carfilzomib: Anticancer Efficacy And Pharmacokinetic Studies In Mice, Ji Eun Park, Se-Eun Chun, Derek Alexander Reichel, Jee Sun Min, Su-Chan Lee, Songhee Han, Gongmi Ryoo, Yunseok Oh, Shin-Hyung Park, Heon-Min Ryu, Kyung Bo Kim, Ho-Young Lee, Soo Kyung Bae, Younsoo Bae, Wooin Lee

Pharmaceutical Sciences Faculty Publications

Carfilzomib (CFZ) is a peptide epoxyketone proteasome inhibitor approved for the treatment of multiple myeloma (MM). Despite the remarkable efficacy of CFZ against MM, the clinical trials in patients with solid cancers yielded rather disappointing results with minimal clinical benefits. Rapid degradation of CFZ in vivo and its poor penetration to tumor sites are considered to be major factors limiting its efficacy against solid cancers. We previously reported that polymer micelles (PMs) composed of biodegradable block copolymers poly(ethylene glycol) (PEG) and poly(caprolactone) (PCL) can improve the metabolic stability of CFZ in vitro. Here, we prepared the CFZ-loaded PM, PEG-PCL-deoxycholic …

Using A Respiratory Navigator Significantly Reduces Variability When Quantifying Left Ventricular Torsion With Cardiovascular Magnetic Resonance, Sean M. Hamlet, Christopher M. Haggerty, Jonathan D. Suever, Gregory J. Wehner, Kristin N. Andres, David K. Powell, Richard J. Charnigo, Brandon K. Fornwalt

Electrical and Computer Engineering Faculty Publications

Background: Left ventricular (LV) torsion is an important indicator of cardiac function that is limited by high inter-test variability (50% of the mean value). We hypothesized that this high inter-test variability is partly due to inconsistent breath-hold positions during serial image acquisitions, which could be significantly improved by using a respiratory navigator for cardiovascular magnetic resonance (CMR) based quantification of LV torsion.

Methods: We assessed respiratory-related variability in measured LV torsion with two distinct experimental protocols. First, 17 volunteers were recruited for CMR with cine displacement encoding with stimulated echoes (DENSE) in which a respiratory navigator was used to measure …

Correlation Of Positron Emission Tomography/Computed Tomography Scan With Smoking, Tumor Size, Stage And Differentiation In Head And Neck Cancer Patients, Jordan L. Pleitz, Partha Sinha, Emily V. Dressler, Rony K. Aouad

Otolaryngology--Head & Neck Surgery Faculty Publications

The goal of this study was to identify associations between positron emission tomography/computed tomography (PET/CT) maximum standardized uptake value (SUVmax) in patients presenting with head and neck squamous cell carcinoma (SCC) with tumor site, size, histologic differentiation, smoking, and diabetes. Charts of patients with oropharyngeal and laryngeal SCC who underwent ¹⁸F-fluorodeoxyglucose PET/CT scans were reviewed between May 2007 and August 2013. Statistical analyses included modeling log-transformed SUVmax values by tumor site, size, histologic differentiation, smoking status, and diabetes using unadjusted linear regressions. Differences were considered statistically significant for P< 0.05. A total of 111 patients (54 with oropharynx and 57 with larynx cancers) were included, 83 men and 28 women with an average age of 57.5 years old. There was a significantly higher pack-year smoking history (P = 0.005) in the larynx cancer group. While tumor …

Longitudinal Measurement And Hierarchical Classification Framework For The Prediction Of Alzheimer's Disease, Meiyan Huang, Wei Yang, Qianjin Feng, Wufan Chen, Michael Weiner, Paul Aisen, Ronald Petersen, Clifford R. Jack Jr., William Jagust, John Trojanowki, Arthur W. Toga, Laurel Beckett, Robert C. Green, Andrew Saykin, John Morris, Leslie M. Shaw, Jeffrey Kaye, Joseph Quinn, Lisa Silbert, Betty Lind, Raina Carter, Sara Dolen, Lon S. Schneider, Sonia Pawluczyk, Mauricio Beccera, Liberty Teodoro, Bryan Spann, James Brewer, Helen Vanderswag, Adam Fleisher, Charles D. Smith, Greg A. Jicha, Peter A. Hardy, Partha Sinha, Elizabeth Oates, Gary Conrad

Neurology Faculty Publications

Accurate prediction of Alzheimer’s disease (AD) is important for the early diagnosis and treatment of this condition. Mild cognitive impairment (MCI) is an early stage of AD. Therefore, patients with MCI who are at high risk of fully developing AD should be identified to accurately predict AD. However, the relationship between brain images and AD is difficult to construct because of the complex characteristics of neuroimaging data. To address this problem, we present a longitudinal measurement of MCI brain images and a hierarchical classification method for AD prediction. Longitudinal images obtained from individuals with MCI were investigated to acquire important …

Examining The Activities, Effectiveness, And Contribution Of Local Health Departments Using A National Longitudinal Survey Of Public Health Systems, Lava R. Timsina

Theses and Dissertations--Epidemiology and Biostatistics

Health services research and public health services and systems research in the past have contributed to a strong foundation of evidence-based progress in organizing, financing, and delivering medical care and public health strategies across the United States. The purpose of this dissertation was to examine disparities in public health systems and in the delivery of population health services in communities served by these systems using nationally representative data from the National Longitudinal Survey of Local Public Health Systems (1998, 2006, 2012, and 2014).

Data from the 1998 cohort of 497 local health jurisdictions serving at least 100,000 residents, and from …

Mixture Modeling With Applications In Alzheimer's Disease, Frank Appiah

Theses and Dissertations--Epidemiology and Biostatistics

This dissertation involves an application of mixture of regression models to 114 individuals who are cognitively intact (from the Alzheimer's Disease and Neuroimaging Initiative-ADNI, data). The correct number of components in the model were estimated with the Singular BIC (SBIC), marking the first time it has been applied to such a problem. The smallest true model in conjunction with the approximation of SBIC was fixed at 1. The resulting posterior probabilities from the model were used to estimate the probability of a person transitioning and risk plots were obtained that could in principle be used by clinicians to identify patients …

Influences Of Probability Instruction On Undergraduates' Understanding Of Counting Processes, Kayla Blyman

Theses and Dissertations--Education Sciences

Historically, students in an introductory finite mathematics course at a major university in the mid-south have struggled the most with the counting and probability unit, leading instructors to question if there was a better way to help students master the material. The purpose of this study was to begin to understand connections that undergraduate finite mathematics students are making between counting and probability. By examining student performance in counting and probability, this study provides insights that inform future instruction in courses that include counting and probability. Consequently, this study lays the groundwork for future inquiries in the field of undergraduate …

Improving The Computational Efficiency In Bayesian Fitting Of Cormack-Jolly-Seber Models With Individual, Continuous, Time-Varying Covariates, Woodrow Burchett

Theses and Dissertations--Statistics

The extension of the CJS model to include individual, continuous, time-varying covariates relies on the estimation of covariate values on occasions on which individuals were not captured. Fitting this model in a Bayesian framework typically involves the implementation of a Markov chain Monte Carlo (MCMC) algorithm, such as a Gibbs sampler, to sample from the posterior distribution. For large data sets with many missing covariate values that must be estimated, this creates a computational issue, as each iteration of the MCMC algorithm requires sampling from the full conditional distributions of each missing covariate value. This dissertation examines two solutions to …

Novel Computational Methods For Censored Data And Regression, Yifan Yang

Theses and Dissertations--Statistics

This dissertation can be divided into three topics. In the first topic, we derived a recursive algorithm for the constrained Kaplan-Meier estimator, which promotes the computation speed up to fifty times compared to the current method that uses EM algorithm. We also showed how this leads to the vast improvement of empirical likelihood analysis with right censored data. After a brief review of regularized regressions, we investigated the computational problems in the parametric/non-parametric hybrid accelerated failure time models and its regularization in a high dimensional setting. We also illustrated that, when the number of pieces increases, the discussed models are …