Statistics and Probability Commons^™

Plasma S-Adenosylmethionine, Dnmt Polymorphisms, And Peripheral Blood Line-1 Methylation Among Healthy Chinese Adults In Singapore, Maki Inoue-Choi, Heather H. Nelson, Kim Robien, Erland Arning, Teodoro Bottiglieri, Woon-Puay Koh, Jian-Min Yuan

Epidemiology Faculty Publications

Background

Global hypomethylation of repetitive DNA sequences is believed to occur early in tumorigenesis. There is a great interest in identifying factors that contribute to global DNA hypomethylation and associated cancer risk. We tested the hypothesis that plasma S-adenosylmethionine (SAM) level alone or in combination with genetic variation in DNA methyltransferases (DNMT1, DNMT3A andDNMT3B) was associated with global DNA methylation extent at long interspersed nucleotide element-1 (LINE-1) sequences.

Methods

Plasma SAM level and LINE-1 DNA methylation index were measured using stored blood samples collected from 440 healthy Singaporean Chinese adults during 1994-1999. Genetic polymorphisms of …

Net Reclassification Indices For Evaluating Risk Prediction Instruments: A Critical Review, Kathleen F. Kerr, Zheyu Wang, Holly Janes, Robyn Mcclelland, Bruce M. Psaty, Margaret S. Pepe

UW Biostatistics Working Paper Series

Background Net Reclassification Indices (NRI) have recently become popular statistics for measuring the prediction increment of new biomarkers.

Methods In this review, we examine the various types of NRI statistics and their correct interpretations. We evaluate the advantages and disadvantages of the NRI approach. For pre-defined risk categories, we relate NRI to existing measures of the prediction increment. We also consider statistical methodology for constructing confidence intervals for NRI statistics and evaluate the merits of NRI-based hypothesis testing.

Conclusions Investigators using NRI statistics should report them separately for events (cases) and nonevents (controls). When there are two risk categories, the …

Sensitivity Of Limiting Hurricane Intensity To Sst In The Atlantic From Observations And Gcms, James Elsner, Sarah Strazzo, Thomas H. Jagger, Timothy Larow, Ming Zhao

Publications

No abstract provided.

The Influence Of Rna Editing On Mirna Processing And Gene Regulation, Brent Shepherd, Dr. Evan Johnson

Journal of Undergraduate Research

The emergence of high-throughput DNA sequencing within the past decade has redefined the world of molecular research. Mapping a human genome, a project that cost the United States government almost $3 billion and took 13 years to complete, is now speculated to soon be less than a week-long procedure costing $1000 or less1,2. With high-throughput DNA sequencing machines, we can rapidly process genomic data for relatively cheap amounts of money. As a result, genomic information is becoming more widely available for many different species. In addition to DNA, high-throughput machines can also be used to sequence other nucleotide-based molecules, including …

Reverse Mortgages: A Source Of Stability In A Volatile Interest Market?, Grant Hodgson, Dr. H. Dennis Tolley

Journal of Undergraduate Research

In reverse mortgages, homeowners over the age of 62 take a loan out based on the equity of their home. While reverse mortgages can be beneficial for both the mortgager and mortgagee, there is also a great deal of risk involved because it is possible for the value of the loan to become larger than the equity on the home, depending on interest rates and life time of the mortgage. It is important to have a model that accurately predicts the risk associated with the mortgage. Recognizing and appropriately managing risk is becoming increasingly important as the “baby boom” generation …

Identification Of Important Pathways In Cancerogenesis, Michelle Withers, Dr. W. Evan Johnson

Journal of Undergraduate Research

The human body interacts at a cellular level through a series of events known as biological pathways. These pathways consist of communications at the molecular, cellular, and genetic levels to maintain a healthy, functional body. When the pathways are disrupted, new pathways are formed that can lead to disease. Currently, researchers are trying to understand the role of disrupted and normal pathways in cancer cells. It is necessary to understand the cancerous pathway in order to return the cell to its normal, healthy function.

A Hierarchical Bayesian Method For Evaluating Efficacy Of Traffic Accident Remediation, Andrew Olsen, Dr. C. Shane Reese

Journal of Undergraduate Research

Thousands of people die in automobile crashes each year. Departments of Transportation are working continuously to reduce the number of fatalities through highway safety projects. One of their critical tasks is to evaluate the efficacy of these projects. We have developed a Bayesian hierarchical Poisson regression model that the Utah Department of Transportation may use to evaluate its traffic-accident intervention. The use of this method is illustrated with severe crashes on a raised median on University Parkway from mile 1.20 to mile 1.96.

An Adaptive Bayesian Approach To Threat-Detection Modeling, Bradley Ferguson, Dr. C. Shane Reese

Journal of Undergraduate Research

Detection of biological and chemical threats is an important consideration in the modern national defense policy. Much of the testing and evaluation of threat detection technologies is performed without appropriate uncertainty quantification. Under the guidance of Dr. Shane Reese, my ORCA project dealt with developing a more effective and cost-efficient way of testing threat detection technologies. I utilized a Bayesian Gaussian Process model that allows for a more flexible and robust model t. I also developed an adaptive experimental design scheme that provides more information than a typical experimental design by learning the concentration levels that we are more interested …

Frequency, Intensity, And Sensitivity To Sea Surface Temperature Of North Atlantic Tropical Cyclones In Best-Track And Simulated Data, Sarah Strazzo, James B. Elsner, Jill C. Trepanier, Kerry A. Emanuel

Publications

Synthetic hurricane track data generated from a downscaling approach are compared to best-track (observed) data to analyze differences in regional frequency, intensity, and sensitivity of limiting intensity to sea surface temperature (SST). Overall, the spatial distributions of observed and simulated hurricane counts match well, although there are relatively fewer synthetic storms in the eastern quarter of the basin. Additionally, regions of intense synthetic hurricanes tend to coincide with regions of intense observed hurricanes. The sensitivity of limiting hurricane intensity to SST computed from synthetic data is slightly lower than sensitivity computed from observed data (5.561.31 m s21 (standard error, SE) …

Smart Sampling Of Noble Gases To Detect Underground Nuclear Explosions, Lindsey M. Skelton, Steven Hunter, Charles Carrigan

STAR Program Research Presentations

One element of the Comprehensive Nuclear Test Ban Treaty (CTBT) is the provision for an on site inspection (OSI). The purpose of an OSI is to monitor for the occurrence of an underground nuclear explosion (UNE) in violation of the treaty. Detection of certain rare radioactive noble gases transported to the surface can be an excellent indicator of a UNE. These gases can be very difficult to capture and require specialized sampling methods. This study aims to determine an algorithm that will increase the efficiency of the subsurface gas sampling technique being used to detect UNEs. Continuous sampling of subsurface …

Using The Inverse Transform To Specify Contrasts In Regression And Latent Curve Structural Equation Models, Thomas N. Templin

Nursing Faculty Research Publications

A simple yet general method for specifying contrasts to test hypotheses in regression and latent curve structural equation models is presented. The traditional qualitative variable coding schemes used in multiple regression (e.g., dummy coding) have a more general formulation. Five matrices are involved: The coding scheme, A. The matrix which gives the distribution and ordering of cases, W; WA = X; X is the design matrix. The contrast coefficient matrix C; and C^-1 = A. In practice, only C, C^-1, and A are necessary because the statistical software generates the design matrix. This method has great generality …

Tools And Methods To Optimize The Analysis Of Telescopic Performance Metrics On Sofia, Steven R. Wilson, Holger Jakob, Stefan Teufel, Zaheer Ali, Jeffrey Van Cleve, Brian Eney, Greg Perryman

STAR Program Research Presentations

SOFIA is an infrared observatory mounted on a modified 747 engineered to do infrared astronomy at 45000 feet. The telescope equipment contains a number of sensors and stabilizers that allow the telescope to capture images while mounted in a moving plane. We have developed methods to analyze the performance of the telescope assembly that will help improve the stabilization and image capturing performance of the observatory. Here we present reusable methods to analyze telescope performance data that will enable improvements in the quality of the scientific data that is produced by the SOFIA. This poster focuses on the multi-flight performance …

Testing For A Zero Proportion, Jonathan R. Bradley, David L. Farnsworth

Articles

Tests for a proportion that may be zero are described. The setting is an environment in which there can be misclassifications or misdiagnoses, giving the possibility of nonzero counts from false positives even though no real examples may exist. Both frequentist and Bayesian tests and analyses are presented, and examples are given.

The Unseen And Untold Issues Of Clinical Trials And Research Ethics In Pakistan., Shahan Waheed, Emaduddin Siddiqui

Department of Emergency Medicine

No abstract provided.

Successful Aging And Creativity : An Investigation On Functional Status And Psychological Wellbeing In Older Adults, Mirie E. Levy

Loma Linda University Electronic Theses, Dissertations & Projects

Objectives: While the literature supports the maintenance of functional status as integral to successful aging, the relationship of creativity on functional status has received little attention. Creativity has been associated with health and aging in the research but only a small number of studies have examined creativity interventions to enhance functional status and boost psychological wellbeing.

Methods: A pretest-posttest quasi-experimental design was used to investigate an 8-week creativity intervention on functional status and psychological wellbeing in older adults. Sample subjects were 92 men and women all over age 60. A series of two-way mixed ANOVAs measured differences between treatment and …

Bayesian Statistical Methods In Gene-Environment And Gene-Gene Interaction Studies, Changlu Liu

Dissertations and Theses (Open Access)

Complex diseases such as cancer result from multiple genetic changes and environmental exposures. Due to the rapid development of genotyping and sequencing technologies, we are now able to more accurately assess causal effects of many genetic and environmental factors. Genome-wide association studies have been able to localize many causal genetic variants predisposing to certain diseases. However, these studies only explain a small portion of variations in the heritability of diseases. More advanced statistical models are urgently needed to identify and characterize some additional genetic and environmental factors and their interactions, which will enable us to better understand the causes of …

Characterizations Of Distributions Of Ratio Of Certain Independent Random Variables, Gholamhossein Hamedani

Mathematics, Statistics and Computer Science Faculty Research and Publications

Various characterizations of the distributions of the ratio of two independent gamma and exponential random variables as well as that of two independent Weibull random variables are presented. These characterizations are based, on a simple relationship between two truncated moments ; on hazard function ; and on functions of order statistics.

On Generalized Gamma Convolution Distributions, Gholamhossein Hamedani

Mathematics, Statistics and Computer Science Faculty Research and Publications

We present here characterizations of certain families of generalized gamma convolution distributions of L. Bondesson based on a simple relationship between two truncated moments. We also present a list of well-known random variables whose distributions or the distributions of certain functions of them belong to the class of generalized gamma convolutions.

The Pitman Inequality For Exchangeable Random Vectors, J. Behboodian, Naveen K. Bansal, Gholamhossein Hamedani, Hans Volkmer

Mathematics, Statistics and Computer Science Faculty Research and Publications

In this short article the following inequality called the “Pitman inequality” is proved for the exchangeable random vector (X₁,X₂,…,X_n) without the assumption of continuity and symmetry for each component X_i:

P(|1n∑i=1nXi|≤|∑i=1nαiXi|)≥12 ,

where all αi≥0 are special weights with ∑i=1nαi=1.

Verifying R Code And Visualizing Power Grid Data: Signature Quality Metrics And Gui Development, Emmanuel C. Herrera, Brett Amidan

STAR Program Research Presentations

Verifying R code and visualizing Power Grid data:

Signature Quality Metrics and GUI development

Author: Emmanuel Herrera

Mentors: Brett Amidan and Landon Sego

There are many bioforensic signatures produced by analytical instruments that are expensive to produce and maintain accuracy. SQM is an R package which will provide subject matter experts with tools that will help them assess the specific quality of signatures and determine their accuracy, utility and cost by simple function calls. Many published academic papers were surveyed on the kinds of metrics already being implemented. Once understood how some metrics measured accuracy, the SQM package was duplicated …

Renal Cryoablation: Investigation Of Periprocedural Visualization To Ols And Treatment Response Quantification, Katherine L. Dextraze

Dissertations and Theses (Open Access)

Cryoablation for small renal tumors has demonstrated sufficient clinical efficacy over the past decade as a non-surgical nephron-sparing approach for treating renal masses for patients who are not surgical candidates. Minimally invasive percutaneous cryoablations have been performed with image guidance from CT, ultrasound, and MRI. During the MRI-guided cryoablation procedure, the interventional radiologist visually compares the iceball size on monitoring images with respect to the original tumor on separate planning images. The comparisons made during the monitoring step are time consuming, inefficient and sometimes lack the precision needed for decision making, requiring the radiologist to make further changes later in …

Objective Bayesian Hypothesis Testing And Estimation For The Risk Ratio In A Correlated 2x2 Table With Structural Zero, Xiaohua Bai

All Theses

We illustrate the construction of an objective Bayesian hypothesis testing and point estimation for the risk ratio in a correlated 2x2 table with structural zero. We solve the problem using Bayesian method through the reference prior, and corresponding posterior distribution of the risk ratio can be derived. Then combined the intrinsic discrepancy, an invariant inforamtion-based loss function, provides an integrated objective Bayesian solution to both hypothesis testing and point estimation problems.

Count Time Series And Discrete Renewal Processes, James Livsey

All Dissertations

Most data collected over time has some degree of periodicity (i.e. seasonally varying
traits). Climate, stock prices, football season, energy consumption, wildlife sightings, and
holiday sales all have cyclical patterns. It should come as no surprise that models that
incorporate periodicity are paramount in the study of time series.
The following work devises time series models for counts (integer-values) that are periodic
and stationary. Foundational work is rst done in constructing a stationary periodic
discrete renewal process (SPDRP). The dynamics of the SPDRP are mathematically interesting
and have many modeling applications, expositions largely unexplored here. This work
develops a SPDRP …

Extreme Value Theory In Periodic Time Series, Zhiyun Gong

All Dissertations

Extreme data points are important in environmental, financial, and insurance settings. In this work, we consider two topics on extremes from environmental data. Many environmental time series have a seasonal structure. The first part presents an approach to identify the rare events of such series based on time series residuals. Here, periodic autoregressive moving-average models are applied to describe the series. The methods justify the application of classical peaks over threshold methods to estimated versions of the one-step-ahead prediction errors of the series. Such methods enable the seasonal means, variances, and autocorrelations of the series to be taken into account. …

Correlates Of Hiv Acquisition In A Cohort Of Black Men Who Have Sex With Men In The United States: Hiv Prevention Trials Network (Hptn) 061, Beryl A. Koblin, Kenneth H. Mayer, Susan H. Eshleman, Lei Wang, Sharon B. Mannheimer, Carlos Del Rio, Steve Shoptaw, Manya Magnus, Susan Buchbinder, Leo Wilton, Ting-Yuan Liu, Vanessa Cummings, Estelle Piwowar-Manning, Sheldon D. Fields, Sam Griffith, Vanessa Elharrar, Darrell Wheeler

Epidemiology Faculty Publications

Background

Black men who have sex with men (MSM) in the United States (US) are affected by HIV at disproportionate rates compared to MSM of other race/ethnicities. Current HIV incidence estimates in this group are needed to appropriately target prevention efforts.

Methods

From July 2009 to October 2010, Black MSM reporting unprotected anal intercourse with a man in the past six months were enrolled and followed for one year in six US cities for a feasibility study of a multi-component intervention to reduce HIV infection. HIV incidence based on HIV seroconversion was calculated as number of events/100 person-years. Multivariate proportional …

Extremal H-Colorings Of Graphs With Fixed Minimum Degree, John Engbers

Mathematics, Statistics and Computer Science Faculty Research and Publications

For graphs G and H, a homomorphism from G to H, or H-coloring of G, is a map from the vertices of G to the vertices of H that preserves adjacency. When H is composed of an edge with one looped endvertex, an H-coloring of G corresponds to an independent set in G. Galvin showed that, for sufficiently large n, the complete bipartite graph K_δ,n-δ is the n-vertex graph with minimum degree δ that has the largest number of independent sets.

In this paper, we begin the project of generalizing this …

Testing The Relative Performance Of Data Adaptive Prediction Algorithms: A Generalized Test Of Conditional Risk Differences, Benjamin A. Goldstein, Eric Polley, Farren Briggs, Mark J. Van Der Laan

U.C. Berkeley Division of Biostatistics Working Paper Series

In statistical medicine comparing the predictability or fit of two models can help to determine whether a set of prognostic variables contains additional information about medical outcomes, or whether one of two different model fits (perhaps based on different algorithms, or different set of variables) should be preferred for clinical use. Clinical medicine has tended to rely on comparisons of clinical metrics like C-statistics and more recently reclassification. Such metrics rely on the outcome being categorical and utilize a specific and often obscure loss function. In classical statistics one can use likelihood ratio tests and information based criterion if the …

Attributing Effects To Interactions, Tyler J. Vanderweele, Eric J. Tchetgen Tchetgen

Harvard University Biostatistics Working Paper Series

A framework is presented which allows an investigator to estimate the portion of the effect of one exposure that is attributable to an interaction with a second exposure. We show that when the two exposures are independent, the total effect of one exposure can be decomposed into a conditional effect of that exposure and a component due to interaction. The decomposition applies on difference or ratio scales. We discuss how the components can be estimated using standard regression models, and how these components can be used to evaluate the proportion of the total effect of the primary exposure attributable to …

The Estimation And Evaluation Of Optimal Thresholds For Two Sequential Testing Strategies, Amber R. Wilk

Theses and Dissertations

Many continuous medical tests often rely on a threshold for diagnosis. There are two sequential testing strategies of interest: Believe the Positive (BP) and Believe the Negative (BN). BP classifies a patient positive if either the first test is greater than a threshold θ1 or negative on the first test and greater than θ2 on the second test. BN classifies a patient positive if the first test is greater than a threshold θ3 and greater than θ4 on the second test. Threshold pairs θ = (θ1, θ2) or (θ3, θ4), depending on strategy, are defined as optimal if they maximized …

Sample Size Considerations In The Design Of Cluster Randomized Trials Of Combination Hiv Prevention, Rui Wang, Ravi Goyal, Quanhong Lei, M. Essex, Victor Degruttola

Harvard University Biostatistics Working Paper Series

No abstract provided.