Statistics and Probability Commons^™

A Generalized Family Of Exponentiated Composite Distributions With Applications To Insurance And Survival Data, Bowen Liu

UNLV Theses, Dissertations, Professional Papers, and Capstones

The concept of composite distributions was proposed in the early 2000s as a good parametric solution to model the data with heavy tails. Since the concept was proposed, it has been widely used in different areas, such as modeling insurance claim size data, predicting the risk measures in insurance data analysis, fitting survival time data, and modeling precipitation data. While a lot of the composite distributions demonstrated great performances in real applications, many commonly used composite distributions such as the inverse gamma-Pareto (IGP) or exponential-Pareto (EP), did not demonstrate great performances when fitting to several particular data sets. In order …

Estimation Of The Parameters In A Mixture Of Two Normal Distributions And The Generalized Pivotal Quantity Method, Md Faruk Hossain

UNLV Theses, Dissertations, Professional Papers, and Capstones

A pivotal quantity is a random variable that is a function of both the random data and the unknown population parameters and whose probability distribution does not depend on any of the unknown parameters. The population parameters here may include nuisance parameters. Historically, pivotal quantities have been used for the construction of test statistics for hypothesis testing of some of these unknown parameters. They have also been used for the construction of confidence intervals for some of these parameters.Generalized pivotal quantities (GPQ) were introduced by Tsui and Weerahandi (1989) and Weerahandi (1993). A GPQ is a function, not only of …

Use Of Healthcare Utilization Records For Analyzing Trends In Clinical Toxoplasmosis: A Comparison Of Nevada And The United States, Elijah Kreutzer

UNLV Theses, Dissertations, Professional Papers, and Capstones

Toxoplasmosis, a zoonotic disease caused by the parasitic protist Toxoplasma gondii, is a ubiquitous, global public health concern with a wide variety of clinical manifestations. Surveillance for the disease is lacking even in developed countries, and what surveillance is present most often focuses on pregnant women. This research investigated trends in clinical toxoplasmosis in Nevada and nationally to address the lack of knowledge concerning how Nevada discharges compare to national discharges in cases of toxoplasmosis. Specifically, this research sought to determine what characterizes toxoplasmosis in Nevada across inpatient, outpatient, and emergency department settings, as well as how these cases differ …

Bayesian Nonparametric Regression Models For Insurance Claims Frequency And Severity, Mostafa Shams Esfand Abadi

UNLV Theses, Dissertations, Professional Papers, and Capstones

The prediction of future insurance claims frequency and severity is one of the most important problems in actuarial science. Such predictions help the actuary set insurance premiums based on observed risk factors, or covariates. Accuracy of these predictions is important from the point of view of both the insurance company as well as the insured customer. Typically, actuaries use parametric regression models to predict claims based on the covariate information. Such models assume the same functional form tying the response to the covariates for each data point. These models are not flexible enough and fail to accurately capture at the …

Retrospective Varying Coefficient Association Analysis Of Longitudinal Binary Traits, Gang Xu

UNLV Theses, Dissertations, Professional Papers, and Capstones

Many genetic studies contain rich information on longitudinal phenotypes that require powerful analytical tools for optimal analysis. Genetic analysis of longitudinal data that incorporates temporal variation is important for understanding the genetic architecture and biological variation of complex diseases. Most of the existing methods assume that the contribution of genetic variants is constant over time and fails to capture the dynamic pattern of disease progression. However, the relative influence of genetic variants on complex traits fluctuates over time.We developed several tests to fill the gap of analyzing time-varying genetic effects in longitudinal GWAS for binary traits. First, we propose a …

Bidirectional Testing For Repairable Systems Reliability: Power Asymmetries, Panel Of Control Charts, And Reliability Graphics, Sung Keun Koo

UNLV Theses, Dissertations, Professional Papers, and Capstones

To a practitioner who chooses to be on the safe side, we offer an option between a cocktail of tests and a solo one-size-fits-all test as a needed antidote to power asymmetries. Two bidirectional tests are first established to empower a basic pair of tests as asymmetrical performances. Unsurprisingly, we’ve seen either bidirectional device championing in one alternative setting, but also being turned against the very setting altered with just one of the composed elements. Progressing by filtering out the bad and enhancing the good, we assemble a hybrid from the empowered pair to restore power symmetries that are thought …

An Empirical Investigation Into The Impact Of Automated Grading, Alex James St. Aubin

UNLV Theses, Dissertations, Professional Papers, and Capstones

Context: Computer Science enrollment has seen increases in recent years. At the University of Nevada, Las Vegas we have seen an average year to year growth rate of 17.33% in the spring and 13.71% in the fall over the past 10 years in our entry level programming course. These enrollment increases have led to considerable additional costs for grading course material.Objective: The goal of this study is to determine the impact of automatic grading systems on students. If automatic grading is at least as effective as manual grading in practice, it may reduce cost under the context of at least …

Exploratory Analysis Of The Associations Between Neonicotinoids And Measures Of Adiposity Among Us Adults: Nhanes 2015–2016, Amruta M. Godbole, Sheniz Moonie, Courtney Coughenour, Cai Zhang, Aimin Chen, Ann M. Vuong

Environmental & Global Health Faculty Research

Background: Toxicology studies suggest that neonicotinoids may be associated with adiposity development via thyroid hormone disruption and increased oxidative stress. Prior epidemiological studies report mixed results for the association between neonicotinoids and adiposity measures.

Objective: To examine the association between detectable concentrations of parent neonicotinoids (imidacloprid, acetamiprid, clothianidin) and neonicotinoid metabolites (5-hydroxy-imidacloprid, N-desmethyl-acetamiprid) with adiposity measures among US adults, and whether sex modifies the associations for neonicotinoid metabolites with adiposity.

Methods: National Health and Nutrition Examination Survey (NHANES) 2015–2016 data was utilized to estimate covariate-adjusted associations between detectable neonicotinoids and fat mass index (FMI), lean mass index (LMI), waist …

Depression And Factors Impacting Quality Of Life Among Adults With Asthma Presence In Nevada, Elizabeth D. Kahane, Lung-Chang Chien, Brian Labus, Dharini M. Bhammar, Jocy-Anna Chevalier, Sheniz Moonie

Epidemiology & Biostatistics Faculty Research

Background: Asthma, a chronic, non-communicable disease has been shown to negatively affect mental health and quality of life among adults. Annually approximately 8% of adult Nevadans report current asthma symptoms and 12.6% report having a lifetime diagnosis. The purpose of this study was to evaluate the association between asthma and depression and explore quality of life factors affecting adult Nevadans with asthma. Methods: Using behavioral risk factor surveillance system (BRFSS) data, this study evaluated the association between self-reported asthma and depression in Nevada using weighted multiple logistic regression. BRFSS asthma call-back survey (ACBS) data were used to determine the frequency …

Cellular Dna Effects Of Radiation And Cancer Risk Assessment In Cells With Mitochondrial Defects, J. Chen, D. M. Sridharan, C. L. Cross, J. M. Pluth

Epidemiology & Biostatistics Faculty Research

Mitochondria play a key role in mediating non-targeted effects (NTE) post-radiation exposure. Mitochondrial DNA (mtDNA), due to its less efficient repair as compared to nuclear DNA, is more severely affected by radiation exposure and mutations in essential mtDNA genes can further exacerbate oxidative stress. Our objective was to evaluate the impact of mitochondrial defects on radiation-induced DDR and genomic instability, biomarkers that can foreshadow cancer development. To better understand this relationship, we used commercially available lymphoblastoid cell lines containing characterized mitochondrial mutations and studied the kinetics of DNA damage and relative telomere length (RTL) changes over time post 0.5 Gy …

Cognitive Effects Of The Bet Protein Inhibitor Apabetalone: A Prespecified Montreal Cognitive Assessment Analysis Nested In The Betonmace Randomized Controlled Trial, Jeffrey Cummings, Gregory G. Schwartz, Stephen J. Nicholls, Aziz Khan, Chris Halliday, Peter P. Toth, Michael Sweeney, Jan O. Johansson, Norman C.W. Wong, Ewelina Kulikowski, Kamyar Kalantar-Zadeh, Kenneth Lebioda, Henry N. Ginsberg, Bengt Winblad, Henrik Zetterberg, Kausik K. Ray

School of Medicine Faculty Research

Background: Epigenetic changes may contribute importantly to cognitive decline in late life including Alzheimer's disease (AD) and vascular dementia (VaD). Bromodomain and extra-terminal (BET) proteins are epigenetic 'readers' that may distort normal gene expression and contribute to chronic disorders. Objective: To assess the effects of apabetalone, a small molecule BET protein inhibitor, on cognitive performance of patients 70 years or older participating in a randomized trial of patients at high risk for major cardiovascular events (MACE). Methods: The Montreal Cognitive Assessment (MoCA) was performed on all patients 70 years or older at the time of randomization. 464 participants were randomized …

Physical And Mental Disabilities Among The Gender-Diverse Population Using The Behavioral Risk Factor Surveillance System, Brfss (2017–2019): A Propensity-Matched Analysis, Jennifer R. Pharr, Kavita Batra

Environmental & Global Health Faculty Research

This propensity-matched analysis utilized the publicly available Behavioral Risk Factor Surveillance System (2017–2019) data to compare the burden of disabilities among transgender/non-binary (TGNB) and cisgender groups. The groups were matched (1:1 ratio) on demographic variables using Nearest Neighborhood Matching. Categorical variables were compared among groups using a Chi-square analysis to test differences in the proportions. Multivariate logistic regression analysis was fit to predict the likelihood of the physical and mental disabilities among the TGNB group compared with the cisgender group while controlling for healthcare access factors, income, and employment. Survey weights were included in the model to account for the …

Joint Displays For Mixed Methods Research In Psychology, Matthew T. Mccrudden, Gwen Marchand, Paul A. Schutz

Research & Economic Development Faculty Research

Mixed methods researchers use joint displays for integration at different phases of the research process in psychological research. Joint displays are visual displays that are used to integrate quantitative and qualitative data during data collection, analysis, and interpretation. We discuss different mixing purposes and how joint displays may help researchers integrate the quantitative and qualitative strands of a study. We provide examples of joint displays for data collection and for data analysis, including newer innovations. Finally, we discuss considerations, including benefits and challenges, of using joint displays during data collection and analysis.

An Exploratory Assessment Of Callings: The Importance Of Specialization, Christopher Paul Cain, Lisa Nicole Cain, James A. Busser, Hee Jung Kang

Hospitality Faculty Research

Purpose This study sought to understand how having a calling influenced engagement, work–life balance and career satisfaction for Professional Golfers Association of America (PGA) and Golf Course Superintendent of America (GCSA) professionals. Design/methodology/approach A conceptual model was used to examine callings among golf course supervisors and its impact on their engagement, work–life balance and career satisfaction. This study also explored the moderation effect of employees’ generalized or specialized role on the calling–engagement relationship. Surveys were collected from a single golf management company and partial least squares structural equation modeling (PLS-SEM) was used for data analysis. Findings The results revealed significant …

Traveling Wave Solutions For Two Species Competitive Chemotaxis Systems, T. B. Issa, Richadi B. Salako, W. Shen

Mathematical Sciences Faculty Research

In this paper, we consider two species chemotaxis systems with Lotka–Volterra competition reaction terms. Under appropriate conditions on the parameters in such a system, we establish the existence of traveling wave solutions of the system connecting two spatially homogeneous equilibrium solutions with wave speed greater than some critical number c∗. We also show the non-existence of such traveling waves with speed less than some critical number c0∗, which is independent of the chemotaxis. Moreover, under suitable hypotheses on the coefficients of the reaction terms, we obtain explicit range for the chemotaxis sensitivity coefficients ensuring c∗=c0∗, which implies that the minimum …

Impact Of Neoantigen Expression And T-Cell Activation On Breast Cancer Survival, Wenjing Li, Amei Amei, Francis Bui, Saba Norouzifar, Lingeng Lu, Zuoheng Wang

Mathematical Sciences Faculty Research

Neoantigens are derived from tumor-specific somatic mutations. Neoantigen-based syn-thesized peptides have been under clinical investigation to boost cancer immunotherapy efficacy. The promising results prompt us to further elucidate the effect of neoantigen expression on patient survival in breast cancer. We applied Kaplan–Meier survival and multivariable Cox regression models to evaluate the effect of neoantigen expression and its interaction with T-cell activation on overall survival in a cohort of 729 breast cancer patients. Pearson’s chi-squared tests were used to assess the relationships between neoantigen expression and clinical pathological variables. Spearman correlation analysis was conducted to identify correlations between neoantigen expression, mutation …

Food Insecurity And Adiposity Among Children And Adults Nhanes 2015-2016, Denise Vidal

UNLV Theses, Dissertations, Professional Papers, and Capstones

Background: Obesity is a preventable disease that has been associated with many adverse health outcomes. A possible factor that may influence adiposity development is food insecurity. Although several epidemiological studies have been conducted examining the association between food insecurity and adiposity among children and adults, results have been inconsistent. Objective: This cross-sectional study investigates the relationship between food insecurity and adiposity among children and adults using recent data from a representative sample of the US population. Methods: We examined 3,391 adults and 2,837 children from the National Health and Nutrition Examination Survey (NHANES) 2015-2016. Household food insecurity was assessed using …

Does Social Support Moderate The Association Between Income And Food Security Status Among Seniors Living In Southern Nevada?, Adugna Teka Siweya

UNLV Theses, Dissertations, Professional Papers, and Capstones

Background: Income is the strongest predictor of food insecurity among seniors, and social support also an essential factor to help mitigate the effects of food insecurity. However, little is known about the potential role that social support may play as a moderator of the association between income and food insecurity. Thus, we aim to examine social support as a moderator for the relationship between income and food insecurity among seniors. Methods: Logistic regression models were used to analyze data collected in 2019 from seniors residing in Southern Nevada. Predictors of food insecurity, sociodemographic factors, social support variables, and income and …

Optimal Two-Stage Designs Based On Restricted Mean Survival Time For A Single-Arm Study, Guogen Shan

School of Public Health Faculty Research

© 2021 The Author(s) Restricted mean survival time is an alternative measure of treatment effect to hazard ratio in clinical trials with time-to-event outcome. The current methods have been focused on one-stage designs. In this article, we propose optimal two-stage designs for a single-arm study with the smallest expected sample size. We compare the performance of the new optimal two-stage designs with the existing one-stage design with regards to the expected sample size and the expected total study length. The simulation results indicate that the new two-stage designs can save the expected sample size substantially as compared to the one-stage …

Addressing The Ecological Fallacy With Lagrangian Inference, Michael Schwob

Calvert Undergraduate Research Awards

Most epidemiologists elect to use statistical models that use population-level data to make inference on the spread of some virus or disease. This has become commonplace in the fields of epidemiology and biostatistics since most data used to construct and verify epidemic models are recorded at the population-level. Obtaining inference from a population-level model may be beneficial in studying the spread of disease in a homogeneous population, but the use of such models to describe a heterogeneous population results in inadequate inference. The inaccuracy of these models is further amplified when one tries to make individual-level inference from these population-level …

Gardasil Vaccine Trends Within Nevada, California, And The U.S.: A Comparative Study, Karen S. Gutierrez

UNLV Theses, Dissertations, Professional Papers, and Capstones

Despite decreasing incidence in cervical cancer in the U.S., there continues to be an increase in public health concern for cervical cancer worldwide. Recent studies report that individuals are disproportionately affected based on region, sex, and race. Additionally, the human papillomavirus (HPV) attributable cancers may be reduced between 70% and 90% through the universal use of HPV-vaccines. In order to expand current knowledge and implement intervention programs in Nevada, it is critical to examine the associations among the Gardasil vaccine, cervical cancer screening, and adverse events following immunization as well as to understand the different socio-demographic subgroups affected. To our …

Bayesian Variable Selection Methods For Genome-Wide Association Studies With Categorical Phenotypes, Benazir Rowe

UNLV Theses, Dissertations, Professional Papers, and Capstones

Genome-wide association studies (GWAS) attempt to find the associations between genetic markers and studied traits (phenotypes). The problem of GWAS is complex and various methods have been developed to approach it. One of such methods is Bayesian variable selection (BVS). We describe the BVS methods in detail and demonstrate the ability of BVS method Posterior Inference via Model Averaging and Subset Selection (piMASS) to improve the power of detecting phenotype-associated genetic loci, potentially leading to new discoveries from existing data without increasing the sample size.

We present several ways to improve and extend the applicability of piMASS for GWAS. The …

Snackjack: A Toy Model Of Blackjack, Stewart N. Ethier, Jiyeon Lee

UNLV Gaming Research & Review Journal

Snackjack is a highly simplified version of blackjack that was proposed by Ethier (2010) and given its name by Epstein (2013). The eight-card deck comprises two aces, two deuces, and four treys, with aces having value either 1 or 4, and deuces and treys having values 2 and 3, respectively. The target total is 7 (vs. 21 in blackjack), and ace-trey is a natural. The dealer stands on 6 and 7, including soft totals, and otherwise hits. The player can stand, hit, double, or split, but split pairs receive only one card per paircard (like split aces in blackjack), and …

Tricyclic Antidepressant Use And Risk Of Fractures: A Meta-Analysis Of Cohort Studies Through The Use Of Both Frequentist And Bayesian Approaches, Qing Wu, Yingke Xu, Yueyang Bao, Jovan Alvarez, Mikee Lianne Gonzales

School of Medicine Faculty Research

Background: Research findings regarding the association between tricyclic antidepressant (TCA) treatment and the risk of fracture are not consistent; we aimed to assess whether people who take TCAs are at an increased fracture risk. Methods: Relevant studies published through June 2020 were identified through database searches of MEDLINE, EMBASE, Scopus, PsycINFO, ISI Web of Science, WorldCat Dissertations and Theses from each database’s inception, as well as through manual searches of relevant reference lists. Two researchers independently performed literature searches, study selection, data abstraction and study appraisal by using a standardized protocol. Frequentist and Bayesian hierarchical random-effects models were used for …

Interplay Of Trna-Derived Fragments And T Cell Activation In Breast Cancer Patient Survival, Nayang Shan, Ningshan Li, Qile Dai, Lin Hou, Xiting Yan, Amei Amei, Lingeng Lu, Zuoheng Wang

Mathematical Sciences Faculty Research

Effector CD8+ T cell activation and its cytotoxic function are positively correlated with improved survival in breast cancer. tRNA-derived fragments (tRFs) have recently been found to be involved in gene regulation in cancer progression. However, it is unclear how interactions between expression of tRFs and T cell activation affect breast cancer patient survival. We used Kaplan–Meier survival and multivariate Cox regression models to evaluate the effect of interactions between expression of tRFs and T cell activation on survival in 1081 breast cancer patients. Spearman correlation analysis and weighted gene co-expression network analysis were conducted to identify genes and pathways that …

Utility Of Inflammatory Markers To Predict Adverse Outcome In Acute Pancreatitis: A Retrospective Study In A Single Academic Center, Mohamad Mubder, Banreet Dhindsa, Danny Nguyen, Syed Saghir, Chad Cross, Ranjit Makar, Gordon Ohning

School of Medicine Faculty Research

Background/Aim: Acute pancreatitis (AP) is a commonly encountered emergency where early identification of complicated cases is important. Inflammatory markers like lymphocyte to monocyte ratio (LMR) and neutrophil to lymphocyte ratio (NLR) are simple and readily available markers. In this study, we evaluated the utility of these markers in the early identification of patients with complicated AP. Patients and Methods: All patients with a diagnosis of AP admitted to the University Medical Center in Las Vegas/Nevada between August 2015 and September 2018 were identified using ICD-10 codes. Medical records were reviewed retrospectively. Epidemiological measures and their associated confidence intervals were calculated …

Physical Therapy Nontreatment Events With Primary Physical Therapist, Stephen Johnson

UNLV Theses, Dissertations, Professional Papers, and Capstones

Background: Physical therapy improves prognosis reduces stay and is generally helpful in aiding recovery from a wide range of ailments. Nontreatment rates occur for multiple reasons and are also related to the personalities of physical therapists.

Methods: We used data from a research project involving physical therapy at an acute care facility in our community. Our study focused on the retrospectively determined primary physical therapist for each patient. We used the chi-squared tests to compare nontreatment rates between days of the week and disease type and the reasons for nontreatment events. Repeated-measure models were used to evaluate the effect of …

Motivational Predictors Of Academic Risk-Taking, Danette Dee Barber

UNLV Theses, Dissertations, Professional Papers, and Capstones

Students benefit when they are willing to engage in optimal challenges (Clifford, 1991). Engagement in challenges, however, comes with academic risks, as failure may be a result. This study investigated motivational factors, including expectancy, subjective task value, mastery goal orientation, and performance avoidance goal orientation as predictors of achievement-related outcomes, including course grade and academic risk-taking. Data were collected from 317 university students enrolled in education classes. Students were given a reading passage and asked to choose questions to answer based on the passage. Students who chose harder questions were categorized as taking more risk. Students also answered questions about …

Accurate Confidence Intervals For Risk Difference In Meta-Analysis With Rare Events, Tao Jiang, Baixin Cao, Guogen Shan

Environmental & Global Health Faculty Research

Background: Meta-analysis provides a useful statistical tool to effectively estimate treatment effect from multiple studies. When the outcome is binary and it is rare (e.g., safety data in clinical trials), the traditionally used methods may have unsatisfactory performance. Methods: We propose using importance sampling to compute confidence intervals for risk difference in meta-analysis with rare events. The proposed intervals are not exact, but they often have the coverage probabilities close to the nominal level. We compare the proposed accurate intervals with the existing intervals from the fixed- or random-effects models and the interval by Tian et al. (2009). Results: We …

Residual-Matching: An Efficient Alternative To Random Sampling In Human Subjects Research Recruitment, Andrew Hooyman, Matthew J. Huentelman, Sydney Y. Schaefer

Kinesiology and Nutrition Sciences Faculty Research

Given the time- and resource-intense nature of human subjects research, we have developed a more intelligent approach to participant recruitment above and beyond random sampling that leverages pilot or preliminary results to reduce the overall number of participants needed for recruitment from an existing electronic cohort or database. Using open-access data from the General Social Survey (GSS) of the National Opinion Research Center, we generated pilot and validation datasets through a simulation to establish moderate and weak relationships based on linear regression. We then compared the performance of our residual-matching method against random sampling in their probabilities of achieving a …