Statistics and Probability Commons^™

Using Cone Beam Computed Tomography To Identify A Prediction Model For Obstructive Sleep Apnea, Jodi Parker

Loma Linda University Electronic Theses, Dissertations & Projects

Introduction: Obstructive Sleep Apnea (OSA) patients have increased risk of morbidity and mortality. Early diagnosis may reduce morbidity and mortality. Prediction of OSA from imaging may help to identify OSA patients earlier in life. CBCT can be used for OSA diagnostic imaging due to its three-dimensional (3D) visualization of the upper airway and craniofacial complex. Magnification associated with conventional 2D radiography is eliminated with CBCT, and radiation to the patient is significantly less than previous modalities used to measure craniofacial & airway measurements associated with OSA. During a CBCT scan, the patient's image is taken supine, rather than the upright …

Comparison Of Rationally-Derived And Empirically-Derived Methods For Predicting Failure In Residential Treatment, Jennifer Pester Grattan

Loma Linda University Electronic Theses, Dissertations & Projects

Patient-focused research methods have been used in adult mental health treatment to improve outcomes by tracking individual treatment response and comparing it with expected recovery patterns. One such approach has used rationally- and empirically-derived methods to analyze data from the OQ-45 and identify patients who are not responding as expected to treatment. Treatment is then adjusted, improving outcomes and lowering overall costs.

Similar but less extensive research has shown analogous methods can be used with children and adolescents. This would be particularly useful in residential treatment, which is an expensive and inadequately researched approach. This study used archival data gathered …

Study Of The Four Factor Theory Of Women’S Sexual Function, Julie M. Merrell

Loma Linda University Electronic Theses, Dissertations & Projects

Tiefer, Hall, and Tavris (2002) described factors comprising four categories of female sexual function. They suggested that unique factors need to be examined to understand sexual function in women. Socio-cultural, political, or economic factors, partner and relationship factors, psychological factors, and medical factors were described as aspects of women’s lives that can be the source of sexual dysfunction. In a previous study, Merrell (2007) utilized Tiefer et al’s (2002) four factor model of sexual functioning to examine female sexual functioning looking specifically at body shame, relationship satisfaction, positive and negative affect, sexual self-schema, and overall health. Based on the results …

Profiles Of Drug Endangered Children: Investigation In A Clinical Sample, Imanie Samanmali Wijayaratne

Loma Linda University Electronic Theses, Dissertations & Projects

Despite the increase in children born prenatally exposed to methamphetamine, little is known about the cognitive and neuropsychological outcomes of these children. Research specific to prenatal-methamphetamine exposure is extremely limited and has been primarily restricted to rat studies. This research combined with the few studies examining children prenatally exposed to methamphetamine suggests that methamphetamine-exposure is associated with various cognitive and neuropsychological delays and is impacted by both biological and environmental factors. Given the scarcity of research in this area, the current study used archival data from a psychological assessment clinic to (1) describe the frequency of prenatal methamphetamine-exposure cases, (2) …

Observer Reliability Of Cephalometric Landmark Identification On 3-D Mr Images, Michael S. Pollack

Loma Linda University Electronic Theses, Dissertations & Projects

Introduction: Cephalometric analysis is a cornerstone of orthodontic diagnosis, yet much information is lost when 3-dimensional structures are assessed with 2-dimensional methods. CBCT offers 3-dimensional imaging but at the cost of higher levels of ionizing radiation. Magnetic resonance imaging provides 3-dimensional imaging without ionizing radiation and additionally imparts visualization of soft tissue structures. Prior to employing MR images for cephalometric analysis, reliability of landmark identification must be assessed. The purpose of this study was to evaluate intra- and interobserver reliability in 3-dimensional landmark identification using MR images.

Materials and Methods: Fifteen cranial MR images (3.0 T, MP-RAGE) from subjects between …

Targeted Maximum Likelihood Estimation: A Gentle Introduction, Susan Gruber, Mark J. Van Der Laan

U.C. Berkeley Division of Biostatistics Working Paper Series

This paper provides a concise introduction to targeted maximum likelihood estimation (TMLE) of causal effect parameters. The interested analyst should gain sufficient understanding of TMLE from this introductory tutorial to be able to apply the method in practice. A program written in R is provided. This program implements a basic version of TMLE that can be used to estimate the effect of a binary point treatment on a continuous or binary outcome.

Comparing Risk Scoring Systems Beyond The Roc Paradigm In Survival Analysis, Hajime Uno, Lu Tian, Tianxi Cai, Isaac S. Kohane, L. J. Wei

Harvard University Biostatistics Working Paper Series

No abstract provided.

Combinational Mixtures Of Multiparameter Distributions, Valeria Edefonti, Giovanni Parmigiani

Johns Hopkins University, Dept. of Biostatistics Working Papers

We introduce combinatorial mixtures - a flexible class of models for inference on mixture distributions whose component have multidimensional parameters. The key idea is to allow each element of the component-specific parameter vectors to be shared by a subset of other components. This approach allows for mixtures that range from very flexible to very parsimonious, and unifies inference on component-specific parameters with inference on the number of components. We develop Bayesian inference and computation approaches for this class of distributions, and illustrate them in an application. This work was originally motivated by the analysis of cancer subtypes: in terms of …

Shrinkage Estimation Of Expression Fold Change As An Alternative To Testing Hypotheses Of Equivalent Expression, Zahra Montazeri, Corey M. Yanofsky, David R. Bickel

COBRA Preprint Series

Research on analyzing microarray data has focused on the problem of identifying differentially expressed genes to the neglect of the problem of how to integrate evidence that a gene is differentially expressed with information on the extent of its differential expression. Consequently, researchers currently prioritize genes for further study either on the basis of volcano plots or, more commonly, according to simple estimates of the fold change after filtering the genes with an arbitrary statistical significance threshold. While the subjective and informal nature of the former practice precludes quantification of its reliability, the latter practice is equivalent to using a …

Pattern Recognition For Command And Control Data Systems, Jason Schwier

All Dissertations

To analyze real-world events, researchers collect observation data from an underlying process and construct models to represent the observed situation. In this work, we consider issues that affect the construction and usage of a specific type of model. Markov models are commonly used because their combination of discrete states and stochastic transitions is suited to applications with both deterministic and stochastic components. Hidden Markov Models (HMMs) are a class of Markov model commonly used in pattern recognition. We first demonstrate how to construct HMMs using only the observation data, and no a priori information, by extending a previously developed approach …

The Effects Of Physical Activity And Nutrient Intake On The Risk Of Hip Fracture : Results From The Adventist Health Study-2, Wen-Ling Liao

Loma Linda University Electronic Theses, Dissertations & Projects

This is a two year of follow up study of Adventist Health Study-2 (AHS-2). We assessed the association between physical activity, nutrient intake and risk of hip fracture among peri- and post menopausal Caucasian women using unconditional logistic regression models. All subjects completed a lifestyle questionnaire which including information of physical activity and frequency and portion size of food intake at enrollment into the study (2002-2007). The “Bi-Annual Hospitalization History” questionnaire which included a question about hip fractures due to minor trauma/falls was sent to subjects approximately two years after enrollment, with a response rat of 82.84%. In this cohort, …

Integer-Valued Time Series And Renewal Processes, Yunwei Cui

All Dissertations

This research proposes a new but simple model for stationary time series of integer counts. Previous work in the area has focused on mixture and thinning methods and links to classical time series autoregressive moving-average difference equations; in contrast, our methods use a renewal process to generate a correlated sequence of Bernoulli trials. By superpositioning independent copies of such processes, stationary series with binomial, Poisson, geometric, or any other discrete marginal distribution can be readily constructed. The model class proposed is parsimonious, non-Markov, and readily generates series with either short or long memory autocovariances. The model can be fitted with …

A Sequential Algorithm To Identify The Mixing Endpoints In Liquids In Pharmaceutical Applications, Akriti Saxena

Theses and Dissertations

The objective of this thesis is to develop a sequential algorithm to determine accurately and quickly, at which point in time a product is well mixed or reaches a steady state plateau, in terms of the Refractive Index (RI). An algorithm using sequential non-linear model fitting and prediction is proposed. A simulation study representing typical scenarios in a liquid manufacturing process in pharmaceutical industries was performed to evaluate the proposed algorithm. The data simulated included autocorrelated normal errors and used the Gompertz model. A set of 27 different combinations of the parameters of the Gompertz function were considered. The results …

On Quality Control Measures In Genome-Wide Association Studies: A Test To Assess The Genotyping Quality Of Individual Probands In Family-Based Association Studies And An Application To The Hapmap Data, David W. Fardo, Iuliana Ionita-Laza, Christoph Lange

Biostatistics Faculty Publications

Allele transmissions in pedigrees provide a natural way of evaluating the genotyping quality of a particular proband in a family-based, genome-wide association study. We propose a transmission test that is based on this feature and that can be used for quality control filtering of genome-wide genotype data for individual probands. The test has one degree of freedom and assesses the average genotyping error rate of the genotyped SNPs for a particular proband. As we show in simulation studies, the test is sufficiently powerful to identify probands with an unreliable genotyping quality that cannot be detected with standard quality control filters. …

A Study On Opmtimizing The Cold Chain Logistic System In China, Huizhong Chen

World Maritime University Dissertations

No abstract provided.

The Research On Optimization Of Liner Route Between China To Middle East, Tingyi Chen

World Maritime University Dissertations

No abstract provided.

Research On Value-At-Risk In International Crude Oil Shipping Market, Xiaoyin Cui

World Maritime University Dissertations

No abstract provided.

Research On Decision-Making On Take-Back Models In Reverse Logistics For End-Of-Life Electronic Products, Yiwei Wang

World Maritime University Dissertations

No abstract provided.

Reliability Of The Model For Clustering Of Longitudinal Datasets Of Infant Mortality Rate In India, Ajay Kumar Bansal, S D. Sharma

COBRA Preprint Series

Because of the natural tendency of human beings and heavenly bodies to form groups, the technique of cluster analysis or segmentation analysis find its importance and applications in many fields of study. A model for clustering of time trends was proposed by authors whose beauty is that 2-way dimensions that is the horizontal flow of the trend and vertical distance of the trend from a common base are considered to obtain the natural clusters. In the present paper, the reliability of this model is studied in two steps namely (i) by repeating the analysis but using different interval distance measures …

Estimating The Effect Of Disability On Medicare Expenditures, David Morris Burk

Theses and Dissertations

We consider the effect of disability status on Medicare expenditures. Disabled elderly historically have accounted for a significant portion of Medicare expenditures. Recent demographic trends exhibit a decline in the size of this population, causing some observers to predict declines in Medicare expenditures. There are, however, reasons to be suspicious of this rosy forecast. To better understand the effect of disability on Medicare expenditures, we develop and estimate a model using the generalized method of moments technique. We find that newly disabled elderly generally spend more than those who have been disabled for longer periods of time. Also, we find …

Development Of Scoring Rubrics And Pre-Service Teachers Ability To Validate Mathematical Proofs, Timothy J. Middleton

Mathematics & Statistics ETDs

The basic aim of this exploratory research study was to determine if a specific instructional strategy, that of developing scoring rubrics within a collaborative classroom setting, could be used to improve pre-service teachers facility with proofs. During the study, which occurred in a course for secondary mathematics teachers, the primary focus was on creating and implementing a scoring rubric, rather than on direct instruction about proofs. In general, the study had very mixed results. Statistically, the quantitative data indicated no significant improvement occurred in participants' ability to validate proofs. However, the qualitative results and the considerable improvement by some participants …

Zero-Inflated Censored Regression Models: An Application With Episode Of Care Data, Jonathan P. Prasad

Theses and Dissertations

The objective of this project is to fit a sequence of increasingly complex zero-inflated censored regression models to a known data set. It is quite common to find censored count data in statistical analyses of health-related data. Modeling such data while ignoring the censoring, zero-inflation, and overdispersion often results in biased parameter estimates. This project develops various regression models that can be used to predict a count response variable that is affected by various predictor variables. The regression parameters are estimated with Bayesian analysis using a Markov chain Monte Carlo (MCMC) algorithm. The tests for model adequacy are discussed and …

The Effect Of Correlation In False Discovery Rate Estimation, Armin Schwartzman, Xihong Lin

Harvard University Biostatistics Working Paper Series

No abstract provided.

Meta-Analysis Using Bayesian Hierarchical Models In Organizational Behavior, Michael David Ulrich

Theses and Dissertations

Meta-analysis is a tool used to combine the results from multiple studies into one comprehensive analysis. First developed in the 1970s, meta-analysis is a major statistical method in academic, medical, business, and industrial research. There are three traditional ways in which a meta-analysis is conducted: fixed or random effects, and using an empirical Bayesian approach. Derivations for conducting meta-analysis on correlations in the industrial psychology and organizational behavior (OB) discipline were reviewed by Hunter and Schmidt (2004). In this approach, Hunter and Schmidt propose an empirical Bayesian analysis where the results from previous studies are used as a prior. This …

Modeling Temperature Reduction In Tendons Using Gaussian Processes Within A Dynamic Linear Model, Richard David Wyss

Theses and Dissertations

The time it takes an athlete to recover from an injury can be highly influenced by training procedures as well as the medical care and physical therapy received. When an injury occurs to the muscles or tendons of an athlete, it is desirable to cool the muscles and tendons within the body to reduce inflammation, thereby reducing the recovery time. Consequently, finding a method of treatment that is effective in reducing tendon temperatures is beneficial to increasing the speed at which the athlete is able to recover. In this project, Bayesian inference with Gaussian processes will be used to model …

Toward A Coherent Test For Disparate Impact Discrimination, Jennifer L. Peresie

Indiana Law Journal

Statistics are generally plaintiffs' primary evidence in establishing a prima facie case of disparate impact discrimination. Thus, the use, or misuse, of statistics dictates case outcomes. Lacking a coherent test for disparate impact, courts choose between the two prevailing tests, statistical significance and the four-fifths rule, in deciding cases, and these tests frequently produce opposite results. Litigants thus face considerable uncertainty and the risk that a judge's preferred outcome will dictate which test is applied. This Article recognizes that the two tests perform complementary functions that both play a useful role in determining whether liability should be imposed. statistical significance …

Theory Of Planned Behavior Model Fit Using Atod Prevention Program Data, Ying Jin

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

This report is to test the Theory of Planned Behavior (TpB) model fit using the data collected from the ATOD Prevention Program conducted by the Operation Snowball Program from year 2004 to 2007 in Naperville, Illinois. Measurement Model and Structural Equation Modeling are used as principal modeling methods to test internal consistency of assigned measures for each construct and the dependency between constructs respectively. The results show that the ATOD Prevention Program data does not fit the TpB model perfectly. Extra paths should be added to the original theoretical model in order to obtain a satisfactory model fit.

Section Abstracts: Statistics

Virginia Journal of Science

Abstracts of the Statistics Section for the 87th Annual Meeting of the Virginia Academy of Science, May 27-29, 2009, Virginia Commonwealth University, Richmond, VA.

Time Valuation Of Risk: A Delayed-Bang Approach, Abhishek Pathak

Engineering Management & Systems Engineering Theses & Dissertations

The subject of this thesis is the combined use of engineering economics and survival analysis in estimating time-value of risk-related resources. The discussion includes (1) the need for sustainable risk management, (2) the importance of time-valuation of risk related resources in the allocation or selection among competing risk mitigation alternatives, (3) the convergence of deterministic engineering economics, survivability analysis, and probabilistic analysis, and (4) results and examples of application in the context of prevention of risk event or mitigation of its consequences.

The significance of this thesis is in how three topics: engineering economics, survivability analysis, and probability theory can …

Nonparametric Population Average Models: Deriving The Form Of Approximate Population Average Models Estimated Using Generalized Estimating Equations, Alan E. Hubbard, Mark J. Van Der Laan

U.C. Berkeley Division of Biostatistics Working Paper Series

For estimating regressions for repeated measures outcome data, a popular choice is the population average models estimated by generalized estimating equations (GEE). We review in this report the derivation of the robust inference (sandwich-type estimator of the standard error). In addition, we present formally how the approximation of a misspecified working population average model relates to the true model and in turn how to interpret the results of such a misspecified model.