Physical Sciences and Mathematics Commons^™

Evaluation Of The Survival Effect For Various Treatment Modalities Among Stage Ii And Iii Rectal Cancer Patients In California, 1994-2009, Myung Mi Cho

Loma Linda University Electronic Theses, Dissertations & Projects

Background: European trials evaluating the effect of preoperative (PreOP) versus postoperative chemoradiotherapy (PostOP CRT) found no survival benefit. However, the effect of a change from PostOP to PreOP CRT has not been evaluated in a population-based setting. We sought to evaluate multimodal treatment changes and overall survival for perioperative (PeriOP) CRT versus surgery alone and for PreOP versus PostOP CRT from 1994 through 2009 among patients receiving radical surgery for stage II and III rectal cancer (RC).

Patients and Methods: We conducted a nonconcurrent cohort study evaluating demographic predictors of multimodal therapy for stage II and III RC using …

Analysis Of Alcohol Use Among Pregnant Women In San Luis Obispo County, Samantha Law

Statistics

Drinking alcohol during pregnancy is harmful to the fetus, and can lead to serious alcohol related developmental birth defects. Utilizing prenatal screening, such as the 4P’s Plus© screening tool, during a woman’s first prenatal doctors visit can help educate women and reduce continued alcohol use during pregnancy. Currently the CDC reports that 1 in 13 women in the US drink alcohol while pregnant compared to local reports that 1 in 3 women in San Luis Obispo County continue to drink alcohol during pregnancy. A primary concern for many local county health care experts and organizations is to raise awareness that …

An Analysis Of Risk Reduction Choices In Dcis Breast Cancer Patients, Lauren Soltesz

Statistics

The main focus of this paper was to evaluate possible demographic and clinical characteristics associated with a woman’s choice of breast conserving surgery (BCS), unilateral mastectomy (ULM), or bilateral risk reduction mastectomy (BRRM). The cohort consisted of patients presenting to the City of Hope National Medical Center with ductal carcinoma in situ breast cancer who elected to have cancer directed surgery (N=305). Analyses to examine associations of patient characteristics with type of surgery were conducted using a multinomial logistic regression. Results showed that older women were more likely to choose breast conserving surgery over bilateral risk reduction mastectomy than younger …

Asymptotics For The Arc Length Of A Multivariate Time Series And Its Applications As A Measure Of Risk, Tharanga Wickramarachchi

All Dissertations

The necessity of more trustworthy methods for measuring the risk (volatility) of financial assets has come to the surface with the global market downturn This dissertation aims to propose sample arc length of a time series, which provides a measure of the overall magnitude of the one-step-ahead changes over the observation time period, as a new approach for quantifying the risk. The Gaussian functional central limit theorem is proven under finite second moment conditions. Without loss of generality we consider equally spaced time series when first differences of the series follow a variety of popular stationary models including autoregressive moving …

Visual Data Mining Techniques For Functional Actigraphy Data: An Object-Oriented Approach In R, Abbass Sharif

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Actigraphy, a technology for measuring a subject's overall activity level almost continuously over time, has gained a lot of momentum over the last few years. An actigraph, a watch-like device that can be attached to the wrist or ankle of a subject, uses an accelerometer to measure human movement every minute or even every 15 seconds. Actigraphy data is often treated as functional data. In this dissertation, we discuss what has been done regarding the visualization of actigraphy data, and then we will explain the three main goals we achieved: (i) develop new multivariate visualization techniques for actigraphy data; (ii) …

Objective Bayesian Inference On The Common Mean Of Normal Distributions, Shiyi Tu

All Theses

One of the oldest problems in statistical area is to make inference on a common mean of several different normal populations with unknown and probably unequal variances. There are several different ways to make inference on the common mean. The most common methods are point estimation, hypothesis testing, and interval estimation. Point estimation uses sample data to calculate a single value serving as a best guess for the unknown population mean. Hypothesis testing assumes all populations have the same mean as the null hypothesis. Interval estimation is an interval of possible values of the unknown mean.
In this paper, we …

The Morbidity & Mortality Of Prevalent Heart Failure, Jennifer Kwon

Loma Linda University Electronic Theses, Dissertations & Projects

The first study population included 292 unselected consecutive patients from the LLUMC heart failure clinic who were enrolled in the study from January to July 2006 and were followed up through the end of December 2010. The treatment policy at the clinic was to uptitrate dosages of beta-adrenergic blockade (β-blockers), angiotensin-converting-enzyme inhibitors (ACEi) and angiotensin II receptor blockers (ARB) to the most tolerable levels in order to reach target dosages, as recommended by the Heart Failure Society of America (HFSA). Patients were classified into systolic heart failure (ejection fraction (EF) < 40%) or diastolic heart failure (EF≥40%). All dosages of β-blockers, ACEi and ARB were extracted through chart reviews and were used as the main predictors of the patients' survival. Results from analyses showed that reaching target dosages of β-blockers and ACEi/ARB may increase survival when compared to not reaching target among the systolic HF population (HR_{β_biockers}= 0.64, 95% CI 0.26-1.56 and HR_ACEi/ARB=0.50, …

An Economic Alternative To The C Chart, Ryan William Black

Graduate Theses and Dissertations

Because the probability of Type I error is not evenly distributed beyond upper and lower three-sigma limits the c chart is theoretically inappropriate for a monitor of Poisson distributed phenomena. Furthermore, the normal approximation to the Poisson is of little use when c is small. These practical and theoretical concerns should motivate the computation of true error rates associated with individuals control assuming the Poisson distribution. An economic alternative to the c chart is described as a statistical model of upward shift from c0 to c1 and the two charts are compared in theory. For a range of c chart …

Investigating The Sensitivity Of Goodness-Of-Fit Indices To Detect Measurement Invariance In The Bifactor Model, Jam Khojasteh

Graduate Theses and Dissertations

A Monte Carlo simulation study was conducted to evaluate the sensitivities of five commonly used goodness-of-fit indices to detect metric invariance properties of the bifactor model. The fit indices that performed the best in terms of power were Gamma and Mc. In addition, Gamma, Mc, CFI, and RMSEA all held Type I error to a minimum. However, only Gamma and CFI are recommended to use in the bifactor model because the other GOF indices have cutoff values that are too large. For Gamma and CFI values of -.026 to -.045 and -.004 to -.009, respectively indicate a lack of metric …

On The Distribution Of Quadratic Expressions In Various Types Of Random Vectors, Ali Akbar Mohsenipour

Electronic Thesis and Dissertation Repository

Several approximations to the distribution of indefinite quadratic expressions in possibly singular Gaussian random vectors and ratios thereof are obtained in this dissertation. It is established that such quadratic expressions can be represented in their most general form as the difference of two positive definite quadratic forms plus a linear combination of Gaussian random variables. New advances on the distribution of quadratic expressions in elliptically contoured vectors, which are expressed as scalar mixtures of Gaussian vectors, are proposed as well. Certain distributional aspects of Hermitian quadratic expressions in complex Gaussian vectors are also investigated. Additionally, approximations to the distributions of …

A Study Of Cellular Calcium Dynamics In Culture Using Fluorescence Microscopy – A Statistical And Mathematical Approach, Richard Adekola Idowu

Doctoral Dissertations

Calcium in its ionic form is very dynamic, especially in excitable cells such as muscle and brain cells, moving from the high concentration exterior of the cell to much lower concentrations inside the cell, where calcium is used as a second messenger. In brain cells, and neurons especially, calcium is a key signaling ion involved in memory and learning with excitatory neurotransmitters such as glutamate turning neurons "on." Glutamate excites the neurons in part by causing large and dynamic changes in the intracellular calcium concentration. While these dynamics are essential for normal signaling in the brain, excessive and sustained elevations …

Finding A Better Confidence Interval For A Single Regression Changepoint Using Different Bootstrap Confidence Interval Procedures, Bodhipaksha Thilakarathne

Electronic Theses and Dissertations

Recently a number of papers have been published in the area of regression changepoints but there is not much literature concerning confidence intervals for regression changepoints. The purpose of this paper is to find a better bootstrap confidence interval for a single regression changepoint. ("Better" confidence interval means having a minimum length and coverage probability which is close to a chosen significance level). Several methods will be used to find bootstrap confidence intervals. Among those methods a better confidence interval will be presented.

Modeling Martian Planetary Entry Descent And Landing Using Monte Carlo Driven Response Surface Methodology, Narcrisha S. Norman

Mechanical & Aerospace Engineering Theses & Dissertations

Response surface methodology (RSM) is a statistical method that explores the relationships between several descriptive variables and one or more response variables. For over sixty years, among other areas, it has been utilized in quality engineering, process engineering, aircraft engineering, economics, chemical engineering, automotive engineering and design/technique optimization. In this dissertation, RSM is utilized to produce regression models that represent the planetary entry, descent and landing (EDL) process. A complete understanding of EDL process is an essential component of any planetary exploration. Research in this area is ongoing and confidence in the ability to explore known celestial bodies is growing. …

An Economic Analysis Of Wine Grape Production In The State Of Connecticut, Jeremy L. Jelliffe

Master's Theses

The Connecticut Wine and Vineyard industry has grown at a steady 3.9% per year over the past decade (ATTTB, 2009). Economic models estimate that the wineries sub-sector contributes $38 million dollars to the state economy and direct employment of 106 residents (Lopez et al., 2010). Programs to support and foster further growth of the industry and CT farm vineyard culture include the Department of Agriculture’s CT Wine Trail and the annual CT Wine festival (DOAG, 2010). Farmland preservation groups also support vineyard development since grape growing tends to secure tracts of farmland for long periods of time.

Investment analysis for …

Approximate Methods For Dynamic Portfolio Allocation Under Transaction Costs, Nabeel Butt

Electronic Thesis and Dissertation Repository

The thesis provides robust and efficient lattice based algorithms for solving dynamic portfolio allocation problems under transaction costs. The early part of the thesis concentrates upon developing a toolbox based on multinomial trees. The multinomial trees are shown to provide a reasonable approximation for most popular transaction cost models in the academic literature. The tool, once forged, is implemented in the powerful Mathematica based parallel computing environment. In the second part of the thesis we provide applications of our framework to real world problems. We show re-balancing portfolios is more valuable in an investment environment where the growth and volatility …

Comparative Analysis Of Dispersion Parameter Estimates In Loglinear Modeling: Applied To E-Commerce Sales And Customer Data, Scott Davis

Statistics

When loglinear models are applied to count data the issue of over-dispersion often arises. Moment and maximum likelihood estimation methods in accounting for over-dispersion are widely used because they allow for model checking tools such as Chi-square, F, and likelihood ratio tests. Here is a comparison between R functions that each uses one method; glm.nb uses MLE, and glm.poisson.disp uses MME. The Index of Dissimilarity and visual model selection (ECDF plots) are also incorporated. These are applied to sales data using product and customer information compiled over the last five years that was generously provided by an e-commerce company.

Modeling Sequential Event Times Using Family Data, Balakumar Swaminathan

Electronic Thesis and Dissertation Repository

In genetic epidemiology, families harboring certain genetic mutations are predisposed to successive cancers in their lifetime. This thesis aims to provide reliable estimates of relative risk and age-dependent cumulative risks (penetrance) associated with the mutated gene for successive cancers. We develop a statistical framework for modeling sequential event times arising from family data. A shared frailty model is employed to incorporate the dependence between the two event times. Because families are ascertained through non-random sampling, an ascertainment-corrected retrospective likelihood approach is proposed to account for the non-ignorable sampling design. Simulation studies demonstrate that our proposed method provides unbiased and reliable …

An Efficient Methodology For Learning Bayesian Networks, Emmanuel Owusu Asante-Asamani

Theses and Dissertations

Statistics from the National Cancer Institute indicate that 1 in 8 women will develop Breast cancer in their lifetime. Researchers have developed numerous statistical models to predict breast cancer risk however physicians are hesitant to use these models because of disparities in the predictions they produce. In an effort to reduce these disparities, we use Bayesian networks to capture the joint distribution of risk factors, and simulate artificial patient populations (clinical avatars) for interrogating the existing risk prediction models. The challenge in this effort has been to produce a Bayesian network whose dependencies agree with literature and are good estimates …

Analysis Of Bank Failure And Size Of Assets, Guancun Zhong

UNLV Theses, Dissertations, Professional Papers, and Capstones

The financial health of the banking industry is an important prerequisite for economic stability and growth. Bank failures in the United States have run in cycles largely associated with the collapse of economic bubbles. The number of bank failures has increased dramatically over the last thirty years (Halling and Hayden, 2007). In this thesis, we try to address the following two questions: 1) What is the relationship, if any, between a bank's asset size and its likelihood of failures? 2) How can we use statistical tools to predict the numbers of bank failures in the future? Various modeling techniques are …

Mussel Survivorship, Growth Rate And Shell Decay Rate In The New River Basin Of Tennessee: An Experimental Approach Using Corbicula Fluminea, Grant Andrew Mincy

Masters Theses

The New River Basin (NRB) of Tennessee is home to a number of rare endemic aquatic communities. One such community of particular importance to the area, experiencing a precipitous population decline due to the fouling and pollution of their freshwater systems, is that of freshwater mussels (Bogan 2006). This study in the NRB involves measuring the mortality rates of live Asian clams (Corbicula fluminea) assemblages and the shell decay rates of their death assemblages. This study also examines the decay rates of the native Villosa iris to gather information on molluscan health and the ability of their shells …

Bayesian Adaptive Designs For Early Phase Clinical Trials, Chunyan Cai

Dissertations & Theses (Open Access)

My dissertation focuses mainly on Bayesian adaptive designs for phase I and phase II clinical trials. It includes three specific topics: (1) proposing a novel two-dimensional dose-finding algorithm for biological agents, (2) developing Bayesian adaptive screening designs to provide more efficient and ethical clinical trials, and (3) incorporating missing late-onset responses to make an early stopping decision.

Treating patients with novel biological agents is becoming a leading trend in oncology. Unlike cytotoxic agents, for which toxicity and efficacy monotonically increase with dose, biological agents may exhibit non-monotonic patterns in their dose-response relationships. Using a trial with two biological agents as …

The Construction Of Edmond Halley's 1701 Map Of Magnetic Declination, Lori L. Murray

Electronic Thesis and Dissertation Repository

Using the navigational instruments of his time, Edmond Halley collected data during sea voyages of the HMS Paramore. Following these voyages, in 1701 he published a map showing lines of equal magnetic declination. Magnetic declination or variation is the angular difference between magnetic north and geographical or true north for any point on the earth’s surface. The map has been held up by many as an early, and good, example of statistical graphics. Halley did not reveal the data analytic techniques that he used in his map construction and they remain unknown to this day. Using some mathematical tools of …

A Comparison Of Methods Of Analysis To Control For Confounding In A Cohort Study Of A Dietary Intervention, Esinhart Hali

Theses and Dissertations

Comparing samples from different populations can be biased by confounding. There are several statistical methods that can be used to control for confounding. These include; multiple linear regression, propensity score matching, propensity score/logit of propensity score as a single covariate in a linear regression model, stratified analysis using propensity score quintiles, weighted analysis using propensity scores or trimmed scores. The data were from two studies of a dietary intervention (FIBERR and RNP). The outcome variable was change from baseline to one month for eight outcome measures; fat, fiber, and fruits/ vegetables behavior, fat, fiber, and fruits/vegetables intentions, fat and fruits/vegetables …

An Integrated Screening And Optimization Strategy, Nathaniel Jackson Rohbock

Theses and Dissertations

Within statistical methods, design of experiments (DOE) is well suited to make good inference from a minimal amount of data. Two types of designs within DOE are screening designs and optimization designs. Traditionally, these approaches have been necessarily separated by a gap between the objectives of each design and the methods available. Despite being so separated, in practice these designs are frequently connected by sequential experimentation. In fact, from the genesis of a project, the experimentor often knows that both designs will be necessary to accomplish his objectives. Due to advances in the understanding of experimental designs with complex aliasing …

Does Pair-Matching On Ordered Baseline Measures Increase Power: A Simulation Study, Yan Jin

Theses and Dissertations

It has been shown that pair-matching on an ordered baseline with normally distributed measures reduces the variance of the estimated treatment effect (Park and Johnson, 2006). The main objective of this study is to examine if pair-matching improves the power when the distribution is a mixture of two normal distributions. Multiple scenarios with a combination of different sample sizes and parameters are simulated. The power curves are provided for three cases, with and without matching, as follows: analysis of post-intervention data only, adding baseline as a covariate, and classic pre-post comparison. The study shows that the additional variance reduction provided …

The Effect Of Baseline Cluster Stratification On The Power Of Pre-Post Analysis, Fengjiao Hu

Theses and Dissertations

The purpose of study is to check whether the power of detecting the effect of intervention versus control in a pre- and post-study can be increased by using a stratified randomized controlled design. A stratified randomized controlled design with two study arms and two time points, where strata are determined by clustering on baseline outcomes of the primary measure, is considered. A modified hierarchical clustering algorithm is developed which guarantees optimality as well as requiring each cluster to have at least one subject per study arm. The power is calculated based on simulated bivariate normal distributed primary measures with mixture …

Simultaneous Confidence Intervals For Risk Ratios In The Many-To-One Comparisons Of Proportions, Jungwon Shin

Electronic Thesis and Dissertation Repository

For many-to-one comparisons of independent binomial proportions using their ratios, we propose the MOVER approach generalizing Fieller's theorem to a ratio of proportions by obtaining variance estimates in the neighbourhood of confidence limits for each proportion. We review two existing methods of inverting Wald and score test statistics and compare their performance with the proposed MOVER approach with score limits and Jeffreys limits for single proportions. As an appropriate multiplicity adjustment incorporating correlations between risk ratios, a Dunnett critical value is computed assuming a common, constant correlation of 0.5 instead of plugging in sample correlation coefficients. The simulation results suggest …

Meta-Heuristics Analysis For Technologically Complex Programs: Understanding The Impact Of Total Constraints For Schedule, Quality And Cost, Henry Darrel Webb

Engineering Management & Systems Engineering Projects for D. Eng. Degree

Program management data associated with a technically complex radio frequency electronics base communication system has been collected and analyzed to identify heuristics which may be utilized in addition to existing processes and procedures to provide indicators that a program is trending to failure. Analysis of the collected data includes detailed schedule analysis, detailed earned value management analysis and defect analysis within the framework of a Firm Fixed Price (FFP) incentive fee contract.

This project develops heuristics and provides recommendations for analysis of complex project management efforts such as those discussed herein. The analysis of the effects of the constraints on …

Reliability Models For Hpc Applications And A Cloud Economic Model, Thanadech Thanakornworakij

Doctoral Dissertations

With the enormous number of computing resources in HPC and Cloud systems, failures become a major concern. Therefore, failure behaviors such as reliability, failure rate, and mean time to failure need to be understood to manage such a large system efficiently.

This dissertation makes three major contributions in HPC and Cloud studies. First, a reliability model with correlated failures in a k-node system for HPC applications is studied. This model is extended to improve accuracy by accounting for failure correlation. Marshall-Olkin Multivariate Weibull distribution is improved by excess life, conditional Weibull, to better estimate system reliability. Also, the univariate …

Assessing Movement Of Fish Through Spectral Analysis Of Otolith Life History Scans, Renee Reilly Hoover

OES Theses and Dissertations

The ability to accurately measure movement timing across environmental gradients is fundamental for testing hypotheses in marine ecology that deal with ingress, egress, and migration of fish. Timing and patterns of movement have been estimated using life-history scans of the chemical signatures encoded in fish otoliths (ear stones). I provide a quantitative approach to examining life history scan data using spectral analysis, which retrospectively measures the movement timing for individual fish. Sagittal otoliths from juvenile Atlantic croaker (Micropogonias undulates) and adult black sea bass (Centropristis striata) were sampled using laser ablation inductively coupled plasma mass spectrometry …