Statistics and Probability Commons^™

Geographical Analysis Of Hub City Transit, Joshua Adam Watts

Master's Theses

This study assess Hub City Transit, the public bus system of Hattiesburg, MS. Statistical analysis is used to determine how well the transit system serves low income areas of the city. A 0.5 mile buffer was applied to the bus routes to determine the coverage of the transit system. Areas of disorder along the routes were also assessed to analyze the landscape routes pass through. Lastly, an analysis of ridership on each route was performed to determine the most heavily used areas, as well as to assess where riders are going on each route.

The findings show that Hub City …

Analytical Comparison Of Contrasting Approaches To Estimating Competing Risks Models, Brian Stephen Rickard

Graduate Theses and Dissertations

Survival analysis is a commonly used tool in many fields but has seen little use in education research despite a common number of research questions for which it is well suited. Researchers often use logistic regression instead; however, this omits useful information. In research on retention and graduation for example, the timing of the event is an important piece of information omitted when using logistic regression. A simulation study was conducted to evaluate four methods of analyzing competing risks survival data, Cox proportional hazards regression, Weibull regression, Fine and Gray's Method, and Cox proportional hazards regression with frailty. College student …

A Comparison Of Population-Averaged And Cluster-Specific Approaches In The Context Of Unequal Probabilities Of Selection, Natalie A. Koziol

College of Education and Human Sciences: Dissertations, Theses, and Student Research

Sampling designs of large-scale, federally funded studies are typically complex, involving multiple design features (e.g., clustering, unequal probabilities of selection). Researchers must account for these features in order to obtain unbiased point estimators and make valid inferences about population parameters. Single-level (i.e., population-averaged) and multilevel (i.e., cluster-specific) methods provide two alternatives for modeling clustered data. Single-level methods rely on the use of adjusted variance estimators to account for dependency due to clustering, whereas multilevel methods incorporate the dependency into the specification of the model.

Although the literature comparing single-level and multilevel approaches is vast, comparisons have been limited to the …

A New Approach To Modeling Multivariate Time Series On Multiple Temporal Scales, Tucker Zeleny

Department of Statistics: Dissertations, Theses, and Student Research

In certain situations, observations are collected on a multivariate time series at a certain temporal scale. However, there may also exist underlying time series behavior on a larger temporal scale that is of interest. Often times, identifying the behavior of the data over the course of the larger scale is the key objective. Because this large scale trend is not being directly observed, describing the trends of the data on this scale can be more difficult. To further complicate matters, the observed data on the smaller time scale may be unevenly spaced from one larger scale time point to the …

Incorporating Relaxivities To More Accurately Reconstruct Mr Images, Muge Karaman, Iain P. Bruce, Daniel B. Rowe

Mathematics, Statistics and Computer Science Faculty Research and Publications

Purpose

To develop a mathematical model that incorporates the magnetic resonance relaxivities into the image reconstruction process in a single step.

Materials and methods

In magnetic resonance imaging, the complex-valued measurements of the acquired signal at each point in frequency space are expressed as a Fourier transformation of the proton spin density weighted by Fourier encoding anomalies: T₂^⁎, T₁, and a phase determined by magnetic field inhomogeneity (∆B) according to the MR signal equation. Such anomalies alter the expected symmetry and the signal strength of the k-space observations, resulting in images distorted …

Genetics Of Obesity In Starr County, Texas Mexican Americans, Heather M. Highland

Dissertations and Theses (Open Access)

Currently, over two-thirds of Americans are classified as over-weight or obese. Obesity increases risk for many other diseases including type 2 diabetes, heart disease, stroke, and cancer, making obesity the largest public health problem in America and most other Westernized nations. Hispanics have a higher rate of both obesity and type 2 diabetes, making them a particularly interesting population in which to study obesity. For the last 33 years, the Starr County Health Studies has collected an array of phenotypes and biological samples from residents of Starr County, along Texas-Mexico border. This study includes 825 subjects who were not known …

Survival Analysis For Truncated Data And Competing Risks, Michael Steelman

All Graduate Plan B and other Reports, Spring 1920 to Spring 2023

The purpose of this project is to consider the problems of left truncation and competing risks in analyzing censored survival data, and to compare and contrast various approaches for handling these problems. The motivation for this work comes from an analysis of data from the Cache County Memory Study. Study investigators were interested in the association between early-life psychologically stressful events (e.g., parental or sibling death, or parental divorce, among others) and late-life risk of Alzheimer's disease (AD). While conventional methods for censored survival data can be applied, the presence of left truncation and competing risks (i.e., other adverse events …

Comparing Linear Mixed Models To Meta-Regression Analysis In The Greenville Air Quality Study, Lynsie M. Daley

All Graduate Plan B and other Reports, Spring 1920 to Spring 2023

The effect of air quality on public health is an important issue in need of better understanding. There are many stakeholders, especially in Utah and Cache Valley, where the poor air quality as measured by PM 2.5 levels and consequent inversions can sometimes be the very worst in the nation. This project focuses on comparing two statistical methods used to analyze an important air quality data set from the Greenville Air Quality Study, focusing on a lung function response variable. A linear mixed model, with a random factor for subject, gives slope estimates and their significance for predictor variables of …

Modeling Seed Dispersal And Population Migration Given A Distribution Of Seed Handling Times And Variable Dispersal Motility: Case Study For Pinyon And Juniper In Utah, Ram C. Neupane

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The spread of fruiting tree species is strongly determined by the behavior and range of fruit-eating animals, particularly birds. Birds either consume and digest seeds or carry and cache them at some distance from the source tree. These carried and settled seeds provide some form of distribution which generates tree spread to the new location. Firstly, we modal seed dispersal by birds and introduce it in a dispersal model to estimate seed distribution. Using this distribution, we create a population model to estimate the speed at which juniper and pinyon forest boundaries move.

Secondly, we introduce a fact that bird …

Mindsets, Attitudes, And Achievement In Undergraduate Statistics Courses, Valorie L. Zonnefeld

Faculty Work Comprehensive List

The purpose of this study was to determine the effects of theories of intelligence and an intervention of incremental mindset training on students’ attitudes toward statistics and their mastery of content in an introductory statistics college course. The sample was 547 undergraduate students at a small, faith-based, liberal arts college in the Midwest.

A pretest-posttest design was used for the three instruments implemented. The Comprehensive Assessment of Outcomes in a first Statistics course (CAOS) assessed students’ statistical literacy. The Student Attitudes Towards Statistics – 36© (SATS©) assessed six components of students’ attitudes toward statistics including affect, cognitive competence, difficulty, effort, …

Roulette: More Than Just A Chance, David Abuhanna

Honors College Theses

Data were generated using a physical roulette wheel to test whether an association exists between initial conditions (the pocket from which the ball is released) and output (the pocket where the ball lands). I have generated data to determine whether there exists statistical significance in distributions of adjoined pockets. Using the statistical software Excel for data tabulation and mapping and using R for statistical computations, I determined a possible method for cheating. I also established an association does in fact exist between initial conditions and output. The existence of this association diminishes roulette as a game of "pure" chance. The …

The Effects Of Instruction On Landing Strategies In Female College-Aged Dancers And Non-Dancers: A Pilot Study, Brittany Keating, Jason Pyfer, Kimberly Vialpando

UNLV Theses, Dissertations, Professional Papers, and Capstones

Background Female athletic participation has increased over the past decade and with it the prevalence of knee injuries. Current research demonstrates an increased risk of anterior cruciate ligament (ACL) injury for female athletes. However, a number of studies have pointed out that ballet and modern dancers exhibit a lower incidence of ACL injuries despite the fact that they perform jumping and landing frequently.

Objective The objective of this study was to examine how dance experience and instruction affect the lower extremity biomechanics during drop landings. Specifically, lower extremity joint alignment and muscle activation of gluteus maximus and gluteus medius were …

The Effects Of Enhanced And Decreased Expectations On Balance Performance In Those With And Without Parkinson’S Disease, Joshua Ostrander, Granuaile Parrish, Jacob Blood

UNLV Theses, Dissertations, Professional Papers, and Capstones

Background: It has been reported individuals typically perform well on a task when enhanced expectancy was provided prior to task performance. It has also been reported people with Parkinson’s disease (PD) are especially susceptible to pre-task placebo cuing and suggestion. Evidence of this susceptibility has been previously demonstrated through brain imaging studies and with demonstration by individuals with PD improved balance performance.

Objective: This study was designed to further previous studies’ results for improved task performance with enhanced expectancy. The purpose of this study was to investigate if the pre-task verbal delivery of enhanced expectancy, decreased expectancy and no expectancy …

Comparing Usability And Variance Of Low- And High Technology Approaches To Gait Analysis In Health Adults, John Mcconnell, Brian Silverman

UNLV Theses, Dissertations, Professional Papers, and Capstones

Purpose: The purpose of this study was to compare the usability, reliability, and objectivity of four tools that represented varying gait analysis technologies used in clinical practice and/or research. Low technology clinical tools included the Gait Abnormality Rating Scale (GARS-M) and the Rancho Los Amigos Observational Gait Analysis (Rancho OGA). High technology tools included the GAITRiteÒ computerized walkway, and the APDM Mobility LabÔ wearable sensor system.

Subjects: 74 healthy adults ages 18-41 years (mean = 24.82, SD = 4.39) 33 males and 40 females.

Methods: Subjects were instructed to walk at a self-selected speed for two minutes …

Four Weeks Of Minimalist Style Running Training Reduced Lumbar Paraspinal Muscle Activation During Shod Running, Stephanie Barton, David Brown, Talia Joyce

UNLV Theses, Dissertations, Professional Papers, and Capstones

Background and Purpose: Research has shown that the risk of low back dysfunctions in runners is related to the increased mileage of distance running. Repetitive shock loading of the spinal structures during running has been indicated as one of the important biomechanical mechanisms underlying such injury. Acute changes in foot strike pattern, like those seen during minimalist style running, have been shown to lead to modifications in lumbar range of motion. Minimalist style running could lead to changes in lumbar biomechanics and muscle activation, potentially reducing the loading on the musculoskeletal structures of the lower back. However, the long term …

Exact Statistical Inferences For Functions Of Parameters Of The Log-Gamma Distribution, Joseph F. Mcdonald

UNLV Theses, Dissertations, Professional Papers, and Capstones

The log-gamma model has been used extensively for flood frequency analysis and is an important distribution in reliability, medical and other areas of lifetime testing. Conventional methods fails to provide exact solutions for the log-gamma model while asymptotic methods provide approximate solutions that often have poor performance for typical sample sizes. The two parameter log-gamma distribution is examined using the generalized p-value approach. The methods are exact in the sense that the tests and the confidence intervals are based on exact probability statements rather than on asymptotic approximations. Exact tests and exact confidence intervals for the parameter of interest based …

A Study Of Sequential Inference For The Risk Ratio And Measure Of Reduction Of Two Binomials, Zhou Wang

UNLV Theses, Dissertations, Professional Papers, and Capstones

The binomial distribution is one of the most commonly and widely occurring probabilistic phenomena in our lives. Since observations from independent Bernoulli trials yield a dichotomous type, the distribution of sequences provides the basis and clue for statistical formulations of a wide variety of problems.

Occasionally, the core of biomedical studies is related to the comparison and evaluation of the risks of events or outcomes of interest in comparing populations under study. For instance, one wishes to compare two groups of subjects drawn from two independent populations. Then, two sample proportions play central roles in those comparisons. One of the …

Failing To Replicate: Hypothesis Testing As A Crucial Key To Make Direct Replications More Credible And Predictable, Pedro Fernando Mateu Bullón

Dissertations

Theory cannot be fully validated unless the original results have been replicated, resulting in conclusion consistency. Replications are the strongest source to verify research findings and knowledge claims. Sciences such as medicine, chemistry, physics, genetics, and biology, are considered successful because their knowledge claims are buttressed by a large set of replications of original studies. Unfortunately in the social sciences many attempts to replicate fail and thus there is a continuing need for replication studies to confirm facts, expand knowledge to gain new understanding, and verify hypotheses. Two plausible explanations for the failure to replicate in the social sciences could …

Three Essays On Panel Data Estimation, Alexander Houser

Dissertations

This work discusses various aspects of panel data estimation. In chapter one, an algorithm for semiparametric random effects estimation is proposed. The performance of bootstrap-based confidence intervals for the proposed estimators are examined and found reasonable. The algorithm is also applied to a set of U.S. state level medical expenditure data to estimate the medical Engel curve. In the second chapter, the predictive performance of various parametric and semiparametric panel data estimators is compared on the same dataset of U.S. state level medical expenditures as well as out of sample forecast performance and bootstrap bias-corrected mean square errors of the …

Annotation Tools For Multivariate Gene Set Testing Of Non-Model Organisms, Russell K. Banks

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Microarray chip technology enables researchers to obtain measures of gene activity for essentially all genes in an organism. After grouping genes into biologically meaningful sets, researchers employ certain statistical tests to identify which gene sets (biological processes) show different levels of activity across different treatment groups. The idea is to identify which biological processes are significantly affected by a certain treatment/condition in a given organism.

Non-model organisms (such as sheep) are not widely studied so gene set membership information is not always readily accessible. This thesis work utilizes two microarray studies involving sheep to provide researchers with working examples of …