Statistics and Probability Commons^™

Exploring The Relationship Between Mandatory Helmet Use Regulations And Adult Cyclists’ Behavior In California Using Hybrid Machine Learning Models, Fatemeh Davoudi Kakhki, Maria Chierichetti

Mineta Transportation Institute

In California, bike fatalities increased by 8.1% from 2015 to 2016. Even though the benefits of wearing helmets in protecting cyclists against trauma in cycling crash has been determined, the use of helmets is still limited, and there is opposition against mandatory helmet use, particularly for adults. Therefore, exploring perceptions of adult cyclists regarding mandatory helmet use is a key element in understanding cyclists’ behavior, and determining the impact of mandatory helmet use on their cycling rate. The goal of this research is to identify sociodemographic characteristics and cycling behaviors that are associated with the use and non-use of bicycle …

Marginally Interpretable Models And Multilevel Models For Quantile Regression With Random-Effects, Nahid Sultana Sumi

Theses and Dissertations

The quantile regression model is an active area of statistical research that has received a lot of attention. This complements the most widely used statistical tool, that is, mean regression analysis. Quantile regression analysis It has become more flexible because of its properties that include no assumption on the distribution of the response variable, equivalent to monotone transformations, and robustness to outliers. However, regression analysis offers methodological challenges if the observations are not independent. Cluster, multilevel, and repeated measures (longitudinal data) designs introduce such dependence. The correlation between observations on the same units or clusters should be accounted for to …

Science Is For Everybody: A Resource For Understanding Glaciers, Climate, And Modeling, Emma Watson

Independent Study Project (ISP) Collection

Climate change threatens the existence of glaciers worldwide. In order to properly interact with these changing systems, we must first understand them. Glacial models provide an excellent way to do this; however, the language and mathematical concepts used in their creation is generally inaccessible to a common audience. This project presents an online resource for a general audience to interact with climate science, glaciology, and glacial modeling. Long term goals for the project include the incorporation of a glacial model of Drangajökull, Vestfirðir, NW Iceland. As such, focus for the project includes a literature review of glaciers, Drangajökull in particular, …

The Labyrinth Of Data Collection For Humanitarian Project Funding And Implementation, Maria Alejandra Pulido

Independent Study Project (ISP) Collection

My research concentrates on four NGOs: IOM, IDMC, JIPS, and OCHA which use different tools to collect data and translate the information into evidence for data-driven decision making (DDDM) for the implementation of humanitarian assistance projects. I focus on the importance, advantages, and various data collection tools which help ameliorate the humanitarian sector since it does not have a current professionalized path to enter the workforce. I incorporated four interviews, attended two conferences and analyzed multiple online sources during my project.

Bayesian Calibration Of The Icrp Zirconium Biokinetic Model And Use Of Canned Priors For The Evaluation Of Bioassay, Thomas Raymond Labone

Theses and Dissertations

The International Commission on Radiological Protection (ICRP) publishes biokinetic models that relate measurements of radioactive material in the body and excreta (bioassay) to the amount of the material taken into the body (intake). Given the intake and the biokinetic model, radiation dose to organs and tissues can be calculated. The ICRP approximates the biokinetics of radioactive materials in the body with compartmental models expressed mathematically as a system of ordinary differential equations, for which they provide point estimates of the rate constants. Inaccurate estimates of intake and radiation dose can result in cases where the biokinetics of an individual differ …

Correcting For Measurement Error In The Outcome When Estimating The Distribution Of Time To Pregnancy With The Current Duration Approach, Nicole Nasrallah

Theses and Dissertations

The current duration approach to modeling time-to-pregnancy (TTP) models the length of pregnancy attempt for women that are currently attempting pregnancy. There is a scarcity of studies, let alone TTP studies, that account for measurement error in the outcome. Previously, the benefits of a piecewise constant model with regards to bias in estimates of the survival function with measurement error and the parametric modelling of TTP was shown. In this thesis, correcting for measurement error in the outcome with the current duration approach is explored through piecewise constant models with log-normal measurement error. Five different methods are compared to determine …

Survivability Analysis In The Shadow Of Apollo: Part I - Cislunar Debris Propagation And Spacecraft Vulnerability, Nathan R. Boone, Robert A. Bettinger

Faculty Publications

Although the reality of routine travel and sustained operations and habitation in space likely remains several decades away, the building blocks of space exploration and space system development necessary to realize this reality are currently being laid by peer, near-peer, and emerging space-faring nations. Traditionally, global space operations were notionally limited to near-Earth space, with mission altitudes extending to geosynchronous or even highly elliptical orbits. During the 2010s, however, space operations began moving beyond this paradigm to encompass cislunar space with reinvigorated U.S. initiatives to return to the Moon via the Artemis program, planned commercial space projects, and an accelerated …

The Classification Of Basket Neural Cells In The Mammalian Neocortex, Sreya Pudi

Senior Theses

Basket neuronal cells of the mammalian neocortex have been classically categorized into two or more groups. Originally, it was thought that the large and small types are the naturally occurring groups that emerge from reasons that relate to neurobiological function and anatomical position. Later, a study based on anatomical and physiological features of these neurons introduced a third type, the net basket cell which is intermediate in size as compared to the large and small types. In this study, multivariate analysis was used to test the hypothesis that the large and small types are morphologically distinct groups. The results of …

Estimation Of Odds Ratio In 2 X 2 Contingency Tables With Small Cell Counts, Guohao Zhu

Dissertations

This study is focusing on properties of estimators of odds ratio or its logarithm in case of 2x2 tables with small counts. The odds ratio represents the odds that an outcome of interest will occur given a particular exposure, compared to the odds of the outcome occurring in the absence of that exposure. Both parameters are often used to quantify the strength of association of two binary variables and are common measurements reported in case-control, cohort, and cross-sectional studies.

Because of their wide applicability, both parameters, odds ratio, and its logarithm, have been intensively studied in the literature. However, most …

A New Generating Family Of Distributions: Properties And Applications To The Weibull Exponential Model, El-Sayed A. El-Sherpieny, Salwa Assar, Tamer Helal

Journal of Modern Applied Statistical Methods

A new method for generating family of distributions was proposed. Some fundamental properties of the new proposed family include the quantile, survival function, hazard rate function, reversed hazard and cumulative hazard rate functions are provided. This family contains several new models as sub models, such as the Weibull exponential model which was defined and discussed its properties. The maximum likelihood method of estimation is using to estimate the model parameters of the new proposed family. The flexibility and the importance of the Weibull-exponential model is assessed by applying it to a real data set and comparing it with other known …

Incorporating Molecular Markers And Causal Structure Among Traits Using A Smith-Hazel Index And Structural Equation Models, Juan Valente Hidalgo-Contreras, Josafhat Salinas-Ruiz, Kent M. Eskridge, Stephen P. Baenziger

Department of Statistics: Faculty Publications

The goal in breeding programs is to choose candidates that produce offspring with the best phenotypes. In conventional selection, the best candidate is selected with high genotypic values (unobserved), in the assumption that this is related to the observed phenotypic values for several traits. Multi-trait selection indices are used to identify superior genotypes when a number of traits are to be considered simultaneously. Often, the causal relationship among the traits is well known. Structural equation models (SEM) have been used to describe the causal relationships among variables in many biological systems. We present a method for multi-trait genomic selection that …

Jmasm 55: Matlab Algorithms And Source Codes Of 'Cbnet' Function For Univariate Time Series Modeling With Neural Networks (Matlab), Cagatay Bal, Serdar Demir

Journal of Modern Applied Statistical Methods

Artificial Neural Networks (ANN) can be designed as a nonparametric tool for time series modeling. MATLAB serves as a powerful environment for ANN modeling. Although Neural Network Time Series Tool (ntstool) is useful for modeling time series, more detailed functions could be more useful in order to get more detailed and comprehensive analysis results. For these purposes, cbnet function with properties such as input lag generator, step-ahead forecaster, trial-error based network selection strategy, alternative network selection with various performance measure and global repetition feature to obtain more alternative network has been developed, and MATLAB algorithms and source codes has been …

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 …

Men’S Comfort In Distributing Or Receiving Hiv Self-Test Kits From Close Male Social Network Members In Dar Es Salaam, Tanzania: Baseline Results From The Step Project, Joseph K.B. Matovu, Gaspar Mbita, Akeen Hamilton, Frank Mhando, Wynton M. Sims, Noah Thompson, Albert N. Komba, Jackson Lija, Jiajia Zhang Ph.D., Thomas Van Den Akker, Dustin T. Duncan, Augustine T. Choko, Donaldson F. Conserve

Faculty Publications

Background

A variety of strategies have been used to reach men with HIV self-testing services, including social network-based HIV self-test kits distribution. However, few studies have assessed men’s comfort to distribute to or receive HIV self-test kits from close male friends within the same social network. In this study, we assessed men’s comfort to distribute to and/or receive HIV self-test kits from close male friends and associated factors among men who socialize in networks locally referred to as “camps” in Tanzania.

Methods

Data are from the baseline survey of a cluster-randomized controlled trial conducted in June 2019 with 18 social …

Recognition And Screening For Chagas Disease In The Usa, Rachel Marcus, Andres F. Henao-Martinez, Melissa Nolan Ph.D., Mph, Elizabeth Livingston, Stephen A. Klotz, Robert H. Gilman, Monica Miranda-Schaeubinger, Sheba Meymandi

Faculty Publications

Chagas disease (CD), caused by the protozoan Trypanosoma cruzi, is a public health concern, mainly among countries in South and Central America. However, despite the large number of immigrants from endemic countries living in the USA, awareness of CD is poor in the medical community, and therefore it is significantly underdiagnosed. To avoid the catastrophic cardiac complications of CD and to prevent maternal–fetal transmission, widespread educational programs highlighting the need for diagnosis are urgently needed.

Infer: An R Package For Tidyverse-Friendly Statistical Inference, Simon P. Couch, Andrew P. Bray, Chester Ismay, Evgeni Chasnovski, B. Baumer, Mine Cetinkaya-Rundel

Statistical and Data Sciences: Faculty Publications

infer implements an expressive grammar to perform statistical inference that adheres to the tidyverse design framework (Wickham et al., 2019). Rather than providing methods for specific statistical tests, this package consolidates the principles that are shared among common hypothesis tests and confidence intervals into a set of four main verbs (functions), supplemented with many utilities to visualize and extract value from their outputs.

Blood Biomarkers For Mild Traumatic Brain Injury: A Selective Review Of Unresolved Issues, Daniel B. Hier, Tayo Obafemi-Ajayi, Matthew S. Thimgan, Gayla R. Olbricht, Sima Azizi, Blaine Allen, Bassam A. Hadi, Donald C. Wunsch

Biological Sciences Faculty Research & Creative Works

Background: The use of blood biomarkers after mild traumatic brain injury (mTBI) has been widely studied. We have identified eight unresolved issues related to the use of five commonly investigated blood biomarkers: neurofilament light chain, ubiquitin carboxy-terminal hydrolase-L1, tau, S100B, and glial acidic fibrillary protein. We conducted a focused literature review of unresolved issues in three areas: mode of entry into and exit from the blood, kinetics of blood biomarkers in the blood, and predictive capacity of the blood biomarkers after mTBI.

Findings: Although a disruption of the blood brain barrier has been demonstrated in mild and severe traumatic brain …

Controlled Branching Processes With Continuous Time, Miguel Gonzalez, Manuel Molina, Ines Del Puerto, Nikolay Yanev, George Yanev

School of Mathematical & Statistical Sciences Faculty Publications

A class of controlled branching processes with continuous time is introduced and some limiting distributions are obtained in the critical case. An extension of this class as regenerative controlled branching processes with continuous time is proposed and some asymptotic properties are considered.

Analysis Of Genes (Tmem106b, Grn, Abcc9, Kcnmb2, And Apoe) Implicated In Risk For Late-Nc And Hippocampal Sclerosis Provides Pathogenetic Insights: A Retrospective Genetic Association Study, Adam J. Dugan, Peter T. Nelson, Yuriko Katsumata, Lincoln M. P. Shade, Kevin L. Boehme, Merilee A. Teylan, Matthew D. Cykowski, Shubhabrata Mukherjee, John S. K. Kauwe, Timothy J. Hohman, Julie A. Schneider, Alzheimer’S Disease Genetics Consortium, David W. Fardo

Biostatistics Faculty Publications

Limbic-predominant age-related TDP-43 encephalopathy neuropathologic change (LATE-NC) is the most prevalent subtype of TDP-43 proteinopathy, affecting up to 1/3rd of aged persons. LATE-NC often co-occurs with hippocampal sclerosis (HS) pathology. It is currently unknown why some individuals with LATE-NC develop HS while others do not, but genetics may play a role. Previous studies found associations between LATE-NC phenotypes and specific genes: TMEM106B, GRN, ABCC9, KCNMB2, and APOE. Data from research participants with genomic and autopsy measures from the National Alzheimer’s Coordinating Center (NACC; n = 631 subjects included) and the Religious Orders Study and Memory …

Conservative Unconditionally Stable Decoupled Numerical Schemes For The Cahn-Hilliard-Navier-Stokes-Darcy-Boussinesq System, Wenbin Chen, Daozhi Han, Xiaoming Wang, Yichao Zhang

Mathematics and Statistics Faculty Research & Creative Works

We propose two mass and heat energy conservative, unconditionally stable, decoupled numerical algorithms for solving the Cahn-Hilliard-Navier-Stokes-Darcy-Boussinesq system that models thermal convection of two-phase flows in superposed free flow and porous media. The schemes totally decouple the computation of the Cahn-Hilliard equation, the Darcy equations, the heat equation, the Navier-Stokes equations at each time step, and thus significantly reducing the computational cost. We rigorously show that the schemes are conservative and energy-law preserving. Numerical results are presented to demonstrate the accuracy and stability of the algorithms.

A Southwestern United States Pilot Investigation Of Triatomine–Mite Prevalence, Kyndall C. Dye-Braumuller, Hanna Waltz, Mary K. Lynn, Stephen A. Klotz, Justin O. Schmidt, Alvaro Romero, Marvin Stanley Rodriguez Aquino, Jose Ricardo Palacios Valladares, Pamela Michelle Cornejo Rivas, Melissa Nolan Ph.D., Mph

Faculty Publications

An estimated 70 million persons in the Western Hemisphere are living at risk for Chagas disease, a parasitic infection transmitted to humans by over 156 different competent triatomine insect vector species. Prior Pan American Health Organization insecticide campaigns throughout Latin America in the 1990s and 2000s demonstrated that domestic insecticide spraying had temporary effects, which resulted in the re-establishment of triatomine species within a few years. Serendipitously, our team found ectoparasitic mites parasitizing triatomines collected from the field in multiple locations in the southwestern United States, where human–triatomine interaction was high but human parasite infection remains low. Upon further investigation …

Ratio And Difference Of Average Hazard With Survival Weight: New Measures To Quantify Survival Benefit Of New Therapy, Hajime Uno, Miki Horiguchi

Harvard University Biostatistics Working Paper Series

The hazard ratio (HR) has been the most popular measure to quantify the magnitude of treatment effect on time-to-event outcomes in clinical research. However, the HR estimated by Cox's method has several drawbacks. One major issue is that there is no clear interpretation when the proportional hazards (PH) assumption does not hold, because it is affected by study-specific censoring time distribution in non-PH cases. Another major issue is that the lack of a group-specific absolute hazard value in each group obscures the clinical significance of the magnitude of the treatment effect. Given these, we propose average hazard with survival weight …

Maternal Diet In Pregnancy And Child’S Respiratory Outcomes: An Individual Participant Data Meta-Analysis Of 18 000 Children, Sara M. Mensink-Bout, Evelien R. Van Meel, Johan C. De Jongste, Isabella Annesi-Maesano, Adrien M. Aubert, Jonathan Y. Bernard, Ling-Wei Chen, Cyrus Cooper, Sarah R. Crozier, Wojciech Hanke, Nicholas C. Harvey, James R. Hébert Scd, Barbara Heude, Joanna Jerzynska, Cecily C. Kelleher, John Mehegan, Fionnuala M. Mcauliffe, Catherine M. Phillips, Kinga Polanska, Caroline L. Relton, Nitin Shivappa Mbbs, Mph, Ph.D., Matthew Suderman, Vincent W.V. Jaddoe, Liesbeth Duijts

Faculty Publications

Rationale Severe fetal malnutrition has been related to an increased risk of respiratory diseases later in life, but evidence for the association of a suboptimal diet during pregnancy with respiratory outcomes in childhood is conflicting. We aimed to examine whether a pro-inflammatory or low-quality maternal diet during pregnancy was associated with child's respiratory health.

Methods We performed an individual participant meta-analysis among 18 326 mother–child pairs from seven European birth cohorts. Maternal pro-inflammatory and low-quality diets were estimated by energy-adjusted Dietary Inflammatory Index (E-DII) and Dietary Approaches to Stop Hypertension (DASH) scores. Preschool wheezing and school-age asthma were measured using …

Hiv Infection And The Risk Of World Health Organization-Defined Sudden Cardiac Death, Matthew S. Freiberg, Meredith S. Duncan, Charles Alcorn, Chung-Chou H. Chang, Suman Kundu, Asri Mumpuni, Emily K. Smith, Sarah Loch, Annie Bedigian, Eric Vittinghoff, Kaku So-Armah, Priscilla Y. Hsue, Amy C. Justice, Zian H. Tseng

Biostatistics Faculty Publications

Background

People living with HIV have higher sudden cardiac death (SCD) rates compared with the general population. Whether HIV infection is an independent SCD risk factor is unclear.

Methods and Results

This study evaluated participants from the Veterans Aging Cohort Study, an observational, longitudinal cohort of veterans with and without HIV infection matched 1:2 on age, sex, race/ethnicity, and clinical site. Baseline for this study was a participant's first clinical visit on or after April 1, 2003. Participants were followed through December 31, 2014. Using Cox proportional hazards regression, we assessed whether HIV infection, CD4 cell counts, and/or HIV viral …

Associations Of Circulating Dimethylarginines With The Metabolic Syndrome In The Framingham Offspring Study, Ibrahim Musa Yola, Carlee Moser, Meredith S. Duncan, Edzard Schwedhelm, Dorothee Atzler, Renke Maas, Juliane Hannemann, Rainer H. Böger, Ramachandran S. Vasan, Vanessa Xanthakis

Biostatistics Faculty Publications

BACKGROUND: Circulating levels of the endogenous inhibitor of nitric oxide synthase, asymmetric dimethylarginine (ADMA), are positively associated with the prevalence of metabolic syndrome (MetS) in cross-sectional investigations. It is unclear if circulating ADMA and other methylarginines are associated with incident MetS prospectively.

METHODS: We related circulating ADMA, symmetric dimethylarginine (SDMA), L-arginine (ARG) concentrations (measured with a validated tandem mass spectrometry assay) and the ARG/ADMA ratio to MetS and its components in 2914 (cross-sectional analysis, logistic regression; mean age 58 years, 55% women) and 1656 (prospective analysis, Cox regression; mean age 56 years, 59% women) individuals from the Framingham Offspring Study …

A Computational Study Of Genotype-Phenotype Mutation Patterns, Kamaludin Dingle, Omar Tawfik, Ahmed Aldabagh

Undergraduate Research Symposium

Understanding properties of genotype-phenotype maps is important for understanding biology and evolution. In this project we make a computational study of the statistical effects of genetic mutations, in particular computing the probabilities of each phenotype transitioning to any other phenotype. We also investigate the importance of the local phenotypic environment of a single genotype, and its role in determining mutation transition probabilities. We use HP protein folding, RNA structure, and a simplified GRN matrix model to study these questions.

Estimation Of Conditional Power For Cluster-Randomized Trials With Interval-Censored Endpoints, Kaitlyn Cook, Rui Wang

Statistical and Data Sciences: Faculty Publications

Cluster-randomized trials (CRTs) of infectious disease preventions often yield correlated, interval-censored data: dependencies may exist between observations from the same cluster, and event occurrence may be assessed only at intermittent study visits. This data structure must be accounted for when conducting interim monitoring and futility assessment for CRTs. In this article, we propose a flexible framework for conditional power estimation when outcomes are correlated and interval-censored. Under the assumption that the survival times follow a shared frailty model, we first characterize the correspondence between the marginal and cluster-conditional survival functions, and then use this relationship to semiparametrically estimate the cluster-specific …

Prevalence, Awareness, And Control Of Hypertension Among Bangladeshi Adults: An Analysis Of Demographic And Health Survey 2017-18, Gulam Muhammed Al Kibria, Rajat Das Gupta Ph.D., Jannatun Nayeem

Faculty Publications

Background

The prevalence of hypertension is increasing in Bangladesh, however, few recent studies investigated the proportion of people and factors associated with prevalence, awareness, and control of this condition in this country. This study investigated these among Bangladeshi adults.

Methods

Using Bangladesh Demographic and Health Survey 2017–18 data, a cross-sectional study was conducted. Multilevel logistic regression analysis was employed after descriptive analysis and prevalence estimation.

Results

Among 12,926 persons (mean age: 40 years, 57% women), the prevalence of hypertension was 27.4% (n = 3551), it was 28.4 and 26.2% among females and males, respectively. Among hypertensive people, about 42.4% …

Characterizing Convolutional Neural Network Early-Learning And Accelerating Non-Adaptive, First-Order Methods With Localized Lagrangian Restricted Memory Level Bundling, Benjamin O. Morris

Theses and Dissertations

This dissertation studies the underlying optimization problem encountered during the early-learning stages of convolutional neural networks and introduces a training algorithm competitive with existing state-of-the-art methods. First, a Design of Experiments method is introduced to systematically measure empirical second-order Lipschitz upper bound and region size estimates for local regions of convolutional neural network loss surfaces experienced during the early-learning stages. This method demonstrates that architecture choices can significantly impact the local loss surfaces traversed during training. Next, a Design of Experiments method is used to study the effects convolutional neural network architecture hyperparameters have on different optimization routines' abilities to …

Wavelet Methods For Very-Short Term Forecasting Of Functional Time Series, Jared K. Nystrom

Theses and Dissertations

Space launch operations at Kennedy Space Center and Cape Canaveral Space Force Station (KSC/CCSFS) are complicated by unique requirements for near-real time determination of risk from lightning. Lightning forecast weather sensor networks produce data that are noisy, high volume, and high frequency time series for which traditional forecasting methods are often ill-suited. Current approaches result in significant residual uncertainties and consequentially may result in forecasting operational policies that are excessively conservative or inefficient. This work proposes a new methodology of wavelet-enabled semiparametric modeling to develop accurate and timely forecasts robust against chaotic functional data. Wavelets methods are first used to …