Statistics and Probability Commons^™

Marginal Structural Models With Counterfactual Effect Modifiers, Wenjing Zheng, Zhehui Luo, Mark J. Van Der Laan

U.C. Berkeley Division of Biostatistics Working Paper Series

In health and social sciences, research questions often involve systematic assessment of the modification of treatment causal effect by patient characteristics, in longitudinal settings with time-varying or post-intervention effect modifiers of interest. In this work, we investigate the robust and efficient estimation of the so-called Counterfactual-History-Adjusted Marginal Structural Model (van der Laan and Petersen (2007)), which models the conditional intervention-specific mean outcome given modifier history in an ideal experiment where, possible contrary to fact, the subject was assigned the intervention of interest, including the treatment sequence in the conditioning history. We establish the semiparametric efficiency theory for these models, and …

Conditional Screening For Ultra-High Dimensional Covariates With Survival Outcomes, Hyokyoung Grace Hong, Jian Kang, Yi Li

The University of Michigan Department of Biostatistics Working Paper Series

Identifying important biomarkers that are predictive for cancer patients' prognosis is key in gaining better insights into the biological influences on the disease and has become a critical component of precision medicine. The emergence of large-scale biomedical survival studies, which typically involve excessive number of biomarkers, has brought high demand in designing efficient screening tools for selecting predictive biomarkers. The vast amount of biomarkers defies any existing variable selection methods via regularization. The recently developed variable screening methods, though powerful in many practical setting, fail to incorporate prior information on the importance of each biomarker and are less powerful in …

Analysis And Modeling Of U.S. Army Recruiting Markets, Joshua L. Mcdonald

Theses and Dissertations

The United States Army Recruiting Command (USAREC) is charged with finding, engaging, and ultimately enlisting young Americans for service as Soldiers in the U.S. Army. USAREC must decide how to allocate monthly enlistment goals, by aptitude and education level, across its 38 subordinate recruiting battalions in order to maximize the number of enlistment contracts produced each year. In our research, we model the production of enlistment contracts as a function of recruiting supply and demand factors which vary over the recruiting battalion areas of responsibility. Using county-level data for the period of recruiting year RY2010 through RY2013 mapped to recruiting …

Clustering Theory And Data Driven Health Care Strategies, Takayuki Iguchi

Theses and Dissertations

DoD health care requires reform with growing costs causing concerns of decreased military capability. One proposed radical strategy to fix current health care delivery systems is to organize medical teams around patients with similar treatment requirements. This is a clustering problem; how do you partition the set of patients so that each group has similar treatment needs? We provide advances in clustering theory relevant to this new health care strategy. In particular, we create fast certifiably optimal k-means clustering using what is known as Probably Certifiably Correct (PCC) algorithms which achieves state-of-the-art performance under certain models. Inspired by the health …

Application Of Non-Rated Line Officer Attrition Levels And Career Field Stability, Christine L. Zens

Theses and Dissertations

The Air Force monitors the strength of its active duty officer force and attempts to achieve the difficult challenge of employing a diversity of talent among career specialties and experience levels. This study completes two objectives, predicting future manning levels for 23 career fields, and providing a statistical framework to assess the stability of these fields. The first part of the study applies regression and survival analysis to subpopulations within the active duty Air Force officer corps, and then aggregates them by year to forecast future personnel levels. Four career fields are considered, including Acquisitions (ACQ), Logistics (LOG), Support (SPT), …

Determining The Optimal Work Breakdown Structure For Government Acquisition Contracts, Brian J. Fitzpatrick

Theses and Dissertations

The optimal level of Government Contract Work Breakdown Structure (G-CWBS) reporting for the purposes of Earned Value Management was inspected. The G-Score Metric was proposed, which can quantitatively grade a G-CWBS, based on a new method of calculating an Estimate At Completion (EAC) cost for each reported element. A random program generator created in R replicated the characteristics of DOD program artifacts retrieved from the Cost Analysis Data Enterprise (CADE) system. The generated artifacts were validated as a population, however validation at the demographic combination level using an artificial neural network was inconclusive. Comparative WBS forms were created for a …

Predicting Schedule Duration For Defense Acquisition Programs: Program Initiation To Initial Operational Capability, Christopher A. Jimenez

Theses and Dissertations

Accurately predicting the most realistic schedule for a defense acquisitions program is an extremely difficult task considering the inherent risk and uncertainties present in the early stages of a program. We use a multiple regression analysis to predict schedule duration in a defense acquisition program. The prediction scope of our research is limited to predicting schedule duration from program initiation to initial operation capability (IOC).We use the data from 56 programs across all services, which was acquired from a SAR database created by RAND. We were able to achieve an R2 of 0.429 and an Adjusted R2 of 0.384 in …

Correlation Of Maximal Inspiratory Pressure To Transdiaphragmatic Twitch Pressure In Intensive Care Unit Patients, Gerald S. Supinski, Philip M. Westgate, Leigh Ann Callahan

Internal Medicine Faculty Publications

Background: Respiratory muscle weakness contributes to respiratory failure in ICU patients. Unfortunately, assessment of weakness is difficult since the most objective test, transdiaphragmatic pressure in response to phrenic nerve stimulation (PdiTw), is difficult to perform. While most clinicians utilize maximum inspiratory pressure (Pimax) to assess strength, the relationship of this index to PdiTw has not been evaluated in a large ICU population. The purpose of the present study was to assess both PdiTw and Pimax in ICU patients to determine how these indices correlate with each other, what factors influence these indices, and how well these indices predict outcomes.

Methods: …

Asymptotically Periodic Solutions Of Volterra Integral Equations, Muhammad Islam

Mathematics Faculty Publications

We study the existence of asymptotically periodic solutions of a nonlinear Volterra integral equation. In the process, we obtain the existence of periodic solutions of an associated nonlinear integral equation with infinite delay. Schauder's fixed point theorem is used in the analysis.

Smallest Eigenvalues For A Right Focal Boundary Value Problem, Paul W. Eloe, Jeffrey T. Neugebauer

Mathematics Faculty Publications

We establish the existence of smallest eigenvalues for the fractional linear boundary value problems D^α₀₊u+λ₁p(t)u = 0 and D^α₀₊u+λ₂q(t)u = 0, 0

A Fast High-Precision Six-Degree-Of-Freedom Relative Position Sensor, Gary B. Hughes, Van P. Macasaet, Janelle Griswold, Claudia A. Sison, Philip Lubin, Peter Meinhold, Johnathan Suen, Travis Brashears, Qicheng Zhang, Jonathan Madajian

Statistics

Lasers are commonly used in high-precision measurement and profiling systems. Some laser measurement systems are based on interferometry principles, and others are based on active triangulation, depending on requirements of the application. This paper describes an active triangulation laser measurement system for a specific application wherein the relative position of two fixed, rigid mechanical components is to be measured dynamically with high precision in six degrees of freedom (DOF). Potential applications include optical systems with feedback to control for mechanical vibration, such as target acquisition devices with multiple focal planes. The method uses an array of several laser emitters mounted …

On The Dynamics Of Boolean Gene Regulatory Networks With Stochasticity, Yuezhe Li

Theses and Dissertations

Genes are responsible for producing proteins that are essential to the construction of complex biological systems. The mechanisms by which this production is regulated have long been the center of wide spread research efforts. Deterministic Boolean gene regulatory models have been a particularly effective avenue of research in this field. However these models fall short of accounting for variations in the gene functionality due to the uncertain internal or external environmental conditions. One of the recent attempts to overcome this weakness is by (Murrugarra, 2012), in which a probabilistic component is introduced as the fixed activation/degradation propensities at the cellular …

A Recommendation System For Meta-Modeling: A Meta-Learning Based Approach, Can Cui, Mengqi Hu, Jeffery D. Weir, Teresa Wu

Faculty Publications

Various meta-modeling techniques have been developed to replace computationally expensive simulation models. The performance of these meta-modeling techniques on different models is varied which makes existing model selection/recommendation approaches (e.g., trial-and-error, ensemble) problematic. To address these research gaps, we propose a general meta-modeling recommendation system using meta-learning which can automate the meta-modeling recommendation process by intelligently adapting the learning bias to problem characterizations. The proposed intelligent recommendation system includes four modules: (1) problem module, (2) meta-feature module which includes a comprehensive set of meta-features to characterize the geometrical properties of problems, (3) meta-learner module which compares the performance of instance-based …

Orbital Simulations On Deflecting Near Earth Objects By Directed Energy, Qicheng Zhang, Kevin J. Walsh, Carl Melis, Gary Hughes, Philip M. Lubin

Statistics

Laser ablation of a near-Earth object (NEO) on a collision course with Earth produces a cloud of ejecta that exerts a thrust on the NEO, deflecting it from its original trajectory. Ablation may be performed from afar by illuminating an Earth-targeting asteroid or comet with a stand-off "DE-STAR" system consisting of a large phased-array laser in Earth orbit. Alternatively, a much smaller stand-on "DE-STARLITE" system may travel alongside the target, slowly deflecting it from nearby over a long period. This paper presents orbital simulations comparing the effectiveness of both systems across a range of laser and NEO parameters. Simulated parameters …

Simulating Longer Vectors Of Correlated Binary Random Variables Via Multinomial Sampling, Justine Shults

UPenn Biostatistics Working Papers

The ability to simulate correlated binary data is important for sample size calculation and comparison of methods for analysis of clustered and longitudinal data with dichotomous outcomes. One available approach for simulating length n vectors of dichotomous random variables is to sample from the multinomial distribution of all possible length n permutations of zeros and ones. However, the multinomial sampling method has only been implemented in general form (without first making restrictive assumptions) for vectors of length 2 and 3, because specifying the multinomial distribution is very challenging for longer vectors. I overcome this difficulty by presenting an algorithm for …

Production Of Biodiesel From Soybean Oil Using Supercritical Methanol, Shriyash Rajendra Deshpande

USF Tampa Graduate Theses and Dissertations

The slow yet steady expansion of the global economies, has led to an increased demand for energy and fuel, which would eventually lead to shortage of fossil fuel resources in the near future. Consequently, researchers have been investigating other fuels like biodiesel. Biodiesel refers to the monoalkyl esters which can be derived from a wide range of sources like vegetable oils, animal fats, algae lipids and waste greases. Currently, biodiesel is largely produced by the conventional route, using an acid, a base or an enzyme catalyst. Drawbacks associated with this route result in higher production costs and longer processing times. …

Strengthening Instrumental Variables Through Weighting, Douglas Lehmann, Yun Li, Rajiv Saran, Yi Li

The University of Michigan Department of Biostatistics Working Paper Series

Instrumental variable (IV) methods are widely used to deal with the issue of unmeasured confounding and are becoming popular in health and medical research. IV models are able to obtain consistent estimates in the presence of unmeasured confounding, but rely on assumptions that are hard to verify and often criticized. An instrument is a variable that influences or encourages individuals toward a particular treatment without directly affecting the outcome. Estimates obtained using instruments with a weak influence over the treatment are known to have larger small-sample bias and to be less robust to the critical IV assumption that the instrument …

Data Publication With The Structural Biology Data Grid Supports Live Analysis, Peter A. Meyer, Stephanie Socias, Jason Key, Elizabeth Ransey, Emily C. Tjon, Alejandro Buschiazzo, Ming Lei, Chris Botka, James Withrow, David Neau, Kanagalaghatta Rajashankar, Karen S. Anderson, Richard H. Baxter, Stephen C. Blacklow, Titus J. Boggon, Alexandre M. J. J. Bonvin, Dominika Borek, Tom J. Brett, Amedeo Caflisch, Chung-I Chang, Walter J. Chazin, Kevin D. Corbett, Michael S. Cosgrove, Sean Crosson, Sirano Dhe-Paganon, Enrico Di Cera, Catherine L. Drennan, Michael J. Eck, Brandt F. Eichman, Qing R. Fan, Oleg V. Tsodikov

Pharmaceutical Sciences Faculty Publications

Access to experimental X-ray diffraction image data is fundamental for validation and reproduction of macromolecular models and indispensable for development of structural biology processing methods. Here, we established a diffraction data publication and dissemination system, Structural Biology Data Grid (SBDG; data.sbgrid.org), to preserve primary experimental data sets that support scientific publications. Data sets are accessible to researchers through a community driven data grid, which facilitates global data access. Our analysis of a pilot collection of crystallographic data sets demonstrates that the information archived by SBDG is sufficient to reprocess data to statistics that meet or exceed the quality of the …

Motorcycle Helmet Effectiveness In Reducing Head, Face And Brain Injuries By State And Helmet Law, Cody S. Olsen, Andrea M. Thomas, Michael Singleton, Anna M. Gaichas, Tracy J. Smith, Gary A. Smith, Justin Peng, Michael J. Bauer, Ming Qu, Denise Yeager, Timothy Kerns, Cynthia Burch, Lawrence J. Cook

Biostatistics Faculty Publications

Background: Despite evidence that motorcycle helmets reduce morbidity and mortality, helmet laws and rates of helmet use vary by state in the U.S.

Methods: We pooled data from eleven states: five with universal laws requiring all motorcyclists to wear a helmet, and six with partial laws requiring only a subset of motorcyclists to wear a helmet. Data were combined in the Crash Outcome Data Evaluation System's General Use Model and included motorcycle crash records probabilistically linked to emergency department and inpatient discharges for years 2005-2008. Medical outcomes were compared between partial and universal helmet law settings. We estimated adjusted relative …

Evaluating The Impact Of A Hiv Low-Risk Express Care Task-Shifting Program: A Case Study Of The Targeted Learning Roadmap, Linh Tran, Constantin T. Yiannoutsos, Beverly S. Musick, Kara K. Wools-Kaloustian, Abraham Siika, Sylvester Kimaiyo, Mark J. Van Der Laan, Maya L. Petersen

U.C. Berkeley Division of Biostatistics Working Paper Series

In conducting studies on an exposure of interest, a systematic roadmap should be applied for translating causal questions into statistical analyses and interpreting the results. In this paper we describe an application of one such roadmap applied to estimating the joint effect of both time to availability of a nurse-based triage system (low risk express care (LREC)) and individual enrollment in the program among HIV patients in East Africa. Our study population is comprised of 16;513 subjects found eligible for this task-shifting program within 15 clinics in Kenya between 2006 and 2009, with each clinic starting the LREC program between …

Orbital Simulations On Deflecting Near-Earth Objects By Directed Energy, Qicheng Zhang, Kevin J. Walsh, Carl Melis, Gary B. Hughes, Philip M. Lubin

Statistics

Laser ablation of a Near Earth Object (NEO) on a collision course with Earth produces a cloud of ejecta which exerts a thrust on the NEO, deflecting it from its original trajectory. Ablation may be performed from afar by illuminating an Earth-targeting asteroid or comet with a stand-off “DE-STAR” system consisting of a large phased-array laser in Earth orbit. Alternatively, a much smaller stand-on “DE-STARLITE” system may travel alongside the target, slowly deflecting it from nearby over a long period. This paper presents orbital simulations comparing the effectiveness of both systems across a range of laser and NEO parameters. Simulated …

Non-Human Primates In Neuroscience Research: The Case Against Its Scientific Necessity, Jarrod Bailey, Katy Taylor

Experimentation Collection

Public opposition to non-human primate (NHP) experiments is significant, yet those who defend them cite minimal harm to NHPs and substantial human benefit. Here we review these claims of benefit, specifically in neuroscience, and show that: a) there is a default assumption of their human relevance and benefit, rather than robust evidence; b) their human relevance and essential contribution and necessity are wholly overstated; c) the contribution and capacity of non-animal investigative methods are greatly understated; and d) confounding issues, such as species differences and the effects of stress and anaesthesia, are usually overlooked. This is the case in NHP …

Progression Of Electrocardiographic Abnormalities In Type 1 Diabetes During 16 Years Of Follow‐Up: The Epidemiology Of Diabetes Interventions And Complications (Edic) Study, Elsayed Soliman, Jye-Yu Backlund, Ionut Bebu, Yabing Li, Zhu-Ming Zhang, Patricia A. Cleary, John M. Lachin

GW Biostatistics Center

Background The electrocardiogram (ECG) is an objective tool for cardiovascular disease (CVD) risk assessment.

Methods and Results We evaluated distribution of ECG abnormalities and risk factors for developing new abnormalities in 1314 patients with type 1 diabetes (T1D) from the Epidemiology of Diabetes Interventions and Complications (EDIC) study. Annual ECGs were centrally read. ECG abnormalities were classified as major and minor according to the Minnesota ECG Classification. At EDIC year 1 (baseline), 356 (27.1%) of the participants had at least 1 ECG abnormality (major or minor) whereas 26 (2%) had at least one major abnormality. During 16 years of follow‐up, …

Is The Force Awakened? Publication Trends In Oncology Big Data As Phase Ii Cancerlinq Is Launched, Hind Rafei, Benjamin Viernes, Angelike P. Liappis, Dalia Abdelaziz Mobarek

GW Research Days 2016 - 2020

Background: The American Society of Clinical Oncology launched CancerLinQ project in 2010 to provide real-time data collection, mining and visualization, clinical decision support, and quality feedback. Creation of a big data software platform is currently underway to power the CancerLinQ in the phase II of the project. This would allow for evidence driven practice and rapid learning for cancer care providers. Additionally, adequate knowledge about the utility of Big Data to encourage provider utilization in high Impact Factor (IF) journals is needed. We aimed to assess trends and quality of Big Data published in Oncology.

Methods: Peer-reviewed English …

Counter Machines And Crystallographic Structures, Natasha Jonoska, Mile Krajcevski, Gregory Mccolm

Mathematics and Statistics Faculty Publications

One way to depict a crystallographic structure is by a periodic (di)graph, i.e., a graph whose group of automorphisms has a translational subgroup of finite index acting freely on the structure. We establish a relationship between periodic graphs representing crystallographic structures and an infinite hierarchy of intersection languages DCL_d,d=0,1,2,…, within the intersection classes of deterministic context-free languages. We introduce a class of counter machines that accept these languages, where the machines with d counters recognize the class DCL_d. An intersection of d languages in DCL₁ defines DCL_d. We prove that there is …

Skewed Factor Models Using Selection Mechanisms, Hyoung-Moon Kim, Mehdi Maadooliat, Reinaldo B. Arellano-Valle, Marc G. Genton

Mathematics, Statistics and Computer Science Faculty Research and Publications

Traditional factor models explicitly or implicitly assume that the factors follow a multivariate normal distribution; that is, only moments up to order two are involved. However, it may happen in real data problems that the first two moments cannot explain the factors. Based on this motivation, here we devise three new skewed factor models, the skew-normal, the skew-t, and the generalized skew-normal factor models depending on a selection mechanism on the factors. The ECME algorithms are adopted to estimate related parameters for statistical inference. Monte Carlo simulations validate our new models and we demonstrate the need for skewed factor models …

The Subject Librarian Newsletter, Statistics, Spring 2016, Patti Mccall

Libraries' Newsletters

No abstract provided.

Knowledge And Behavior Change Of People Living With Hiv Through Nutrition Education And Counseling, Fitri Hudayani, Ratu Ayu Dewi Sartika

Kesmas

HIV, AIDS, dan gizi saling berhubungan. Pada Unit Pelayanan Terpadu HIV Rumah Sakit Umum Pusat Nasional Dr. Cipto Mangunkusumo, layanan edukasi dan konseling gizi disediakan secara kolaboratif untuk orang yang hidup dengan HIV. Penelitian ini bertujuan untuk mengetahui pengaruh pendidikan dan konseling gizi terhadap pengetahuan dan perilaku orang yang hidup dengan HIV. Penelitian ini dilakukan dengan desain kuasi eksperimental menggunakan kelompok perlakuan dan kontrol. Kelompok perlakuan terdiri dari 25 sampel dan 29 sampel untuk kelompok kontrol, dilakukan sebelum dan setelah perlakuan. Sampel berusia dewasa antara 18 – 50 tahun dipilih dengan menerapkan kriteria inklusi dan eksklusi. Sampel uji-t berpasangan digunakan …

Influence Of Household Environment And Maternal Behaviors To Upper Respiratory Infection Among Toddlers, Reny Fahdiyani, Ardini S. Raksanagara, Hadyana Sukandar

Kesmas

Infeksi saluran pernapasan akut atas (ISPA atas) di negara berkembang menyebabkan morbiditas tinggi pada anak bawah usia lima tahun (balita). Kementerian Kesehatan Republik Indonesia melaporkan bahwa ISPAnonpneumonia meningkat 2,6% dari tahun 2007 ke 2011. Faktor risiko yang dapat berkontribusi termasuk lingkungan dan perilaku. Penelitian ini bertujuan untuk menyelidiki faktor perilaku dan lingkungan dengan ISPA atas pada balita. Studi kasus kontrol ini dilakukan dari Februari-April 2015 pada balita di Tamansari yang merupakan daerah kumuh di Kota Bandung. Kasus adalah 55 ibu dengan balita menderita ISPA atas yang datang ke puskesmas, sedangkan kontrol dua kali lebih besar dari kasus dipilih dari lingkungan …

Predisposing Factors With Complementary Feeding Practices Among 9-11 Month-Old Infants In Jakarta Urban Slum Area, Septriana Septriana, Gita Ardelia Suhartono

Kesmas

Penyebab utama kekurangan gizi selain dari penyakit infeksi adalah pola asuh yang tidak sesuai dan pemberian makan yang optimal menjadi salah satu cara untuk mengatasi konsekuensi jangka panjang dari kekurangan zat gizi. Penelitian ini bertujuan untuk mengetahui hubungan antara faktor pendukung praktik pemberian makanan pendamping air susu ibu (MPASI) pada bayi usia 9 - 11 bulan di daerah kumuh perkotaan Jakarta. Penelitian potong lintang ini melibatkan 50 orang pengasuh bayi usia 9 – 11 bulan. Data dikumpulkan melalui wawancara menggunakan kuesioner. Tidak terdapat hubungan yang bermakna antara usia pengasuh dengan praktik pemberian makan (nilai p = 0,645). Demikian juga dengan …