Statistics and Probability Commons^™

The Association Of Maternal Intention To Breastfeed, Early Skin-To-Skin Mother/Infant Contact, And Exclusive Breastfeeding During The Maternity Hospital Stay, Leslie Mary Bramson

Loma Linda University Electronic Theses, Dissertations & Projects

Breastfeeding is the optimal method to nourish and nurture an infant. Exclusive breastfeeding rates in the United States have reached the goal of Healthy People 2010 that 75% of mother's breastfeed in the immediate postpartum period. Yet, less than 35% of San Bernardino county mothers and 47.7% of Riverside county mothers are exclusively breastfeeding during their maternity hospital stays, with as many as 50% of the infants being weaned from the breast in the first 14 days of life.

This prospective study examined archived data collected by Perinatal Services Network (PSN) of Loma Linda University Medical Center/Children's Hospital for the …

Nonparametric Regression Using Local Kernel Estimating Equations For Correlated Failure Time Data, Zhangsheng Yu, Xihong Lin

Harvard University Biostatistics Working Paper Series

No abstract provided.

A Comparison Of Methods For Estimating The Causal Effect Of A Treatment In Randomized Clinical Trials Subject To Noncompliance, Rod Little, Qi Long, Xihong Lin

Harvard University Biostatistics Working Paper Series

No abstract provided.

Semiparametric Maximum Likelihood Estimation In Normal Transformation Models For Bivariate Survival Data, Yi Li, Ross L. Prentice, Xihong Lin

Harvard University Biostatistics Working Paper Series

No abstract provided.

Knowledge, Perceptions, Beliefs And Behaviors Related To The Prevention Of Hypertension Among Black Seventh-Day Adventists Living In London, Maxine A. Newell

Loma Linda University Electronic Theses, Dissertations & Projects

This study was a cross-sectional survey of the hypertension (HTN) knowledge and risk behaviors of Black Seventh-day Adventists (SDA) in London. Recruitment took take place in 17 predominantly Black SDA churches in London. A questionnaire assessed knowledge and lay-beliefs about HTN and perceptions towards HTN using the health belief model (HBM) constructs of susceptibility, severity, benefits, barriers, and self-efficacy. Cohen’s Perceived Stress Scale was incorporated into the questionnaire. Blood pressure, height, weight and waist circumference were and current lifestyles practices were evaluated for the presence of HTN risk factors.

Of the 312 volunteers, ages 25 to 79, 55% were born …

Comparison Of Microleakage In Three Sealant Placement Protocols Vs. The Enamel Loc System, Audrey T. Sheu

Loma Linda University Electronic Theses, Dissertations & Projects

PURPOSE: To evaluate sealant microleakage using four different application techniques.

METHODS: The four application techniques evaluated were acid etch only, Adper L-Pop bonding, Optibond bonding, and Enamel Loc One-Step Sealant. Sixty-four extracted third molar teeth were assigned on one of four application techniques (n=16) and Clinpro sealants applied according to the manufacturer's instructions. The teeth were thermocycled for 500 cycles, dyed, and embedded in resin. The samples were then sectioned and evaluated for microleakage on the buccal and lingual surfaces. Statistical methods employed to analyze the data were the Kruskal-Willis rank test and the Mann-Whitney U test.

RESULTS: No significant …

Effect Of Gutta Percha On The Retention Of A Post Using Different Cements, Saeda H. Basta

Loma Linda University Electronic Theses, Dissertations & Projects

This study evaluated the effect of residual gutta percha on the retention strength of prefabricated post cemented with four different cements. Forty intact mandibular single canal canines or premolars were selected for standardized size and quality, endodontically treated, and decoronated to the cementoenamel junction. A post space was prepared to accommodate Para post XP size 4 (Coltene, Whaledent Inc., Cuy Falls, Ohio) to a depth of 8 mm. The Obtura heated gutta percha system was used to inject a very thin line of gutta percha along one lateral wall to the depth of the future post. Forty obturated teeth were …

Doubly Robust Ecological Inference, Daniel B. Rubin, Mark J. Van Der Laan

U.C. Berkeley Division of Biostatistics Working Paper Series

The ecological inference problem is a famous longstanding puzzle that arises in many disciplines. The usual formulation in epidemiology is that we would like to quantify an exposure-disease association by obtaining disease rates among the exposed and unexposed, but only have access to exposure rates and disease rates for several regions. The problem is generally intractable, but can be attacked under the assumptions of King's (1997) extended technique if we can correctly specify a model for a certain conditional distribution. We introduce a procedure that it is a valid approach if either this original model is correct or if we …

The Impact Of Being Born With Cleft And Cleft Reparative Surgery On Overall Health And Speech Outcomes, Khatansuudal Evsanaa

Master's Theses

Orofacial cleft is one of the most common and treatable birth defects in the world. If left untreated, orofacial cleft can impair normal speech development, growth, and could lead to a number of health consequences later in life. The main motivation of the study is to measure the impact of being born with cleft and the cleft reparative surgery on overall speech and health cleft for teenagers in India using difference-in-differences approach along with household fixed effects method. An overall health outcome was measured using height, weight, grip strength and BMI, and the speech acceptability was measured using a “Universal …

Quasigeometric Distributions And Extra Inning Baseball Games, Darren B. Glass, Philip J. Lowry

Math Faculty Publications

Each July, the eyes of baseball fans across the country turn to Major League Baseball’s All-Star Game, gathering the best and most popular players from baseball’s two leagues to play against each other in a single game. In most sports, the All-Star Game is an exhibition played purely for entertainment. Since 2003, the baseball All-Star Game has actually ‘counted’, because the winning league gets home field advantage in the World Series. Just one year before this rule went into effect, there was no winner in the All-Star Game, as both teams ran out of pitchers in the 11th inning and …

Abstracts In High Profile Journals Often Fail To Report Harm, Enrique Bernal-Delgado, Elliot S. Fisher

Dartmouth Scholarship

To describe how frequently harm is reported in the abstract of high impact factor medical journals. We carried out a blinded structured review of a random sample of 363 Randomised Controlled Trials (RCTs) carried out on human beings, and published in high impact factor medical journals in 2003. Main endpoint: 1) Proportion of articles reporting harm in the abstract; and 2) Proportion of articles that reported harm in the abstract when harm was reported in the main body of the article. Analysis: Corrected Prevalence Ratio (cPR) and its exact confidence interval were calculated. Non-conditional logistic regression was used.

Targeted Methods For Biomarker Discovery, The Search For A Standard, Catherine Tuglus, Mark J. Van Der Laan

U.C. Berkeley Division of Biostatistics Working Paper Series

More often than not biomarker studies analyze large quantities of variables with complicated and generally unknown correlation structure. There are numerous statistical methods which attempt to unravel these variables and determine the underlying mechanism through identification of causally related biomarkers. Results from these methods are generally difficult to interpret and nearly impossible to compare across studies. The FDA has currently called for a standardization of methods and protocol for biomarker detection. In response, we propose targeted variable importance (tVIM) as a standardized method for biomarker discovery. Through the use of targeted Maximum Likelihood, tVIM provides double robust estimates of variable …

Marginal Structural Models For Partial Exposure Regimes, Stijn Vansteelandt, Karl Mertens, Carl Suetens, Els Goetghebeur

Harvard University Biostatistics Working Paper Series

Intensive care unit (ICU) patients are ell known to be highly susceptible for nosocomial (i.e. hospital-acquired) infections due to their poor health and many invasive therapeutic treatments. The effects of acquiring such infections in ICU on mortality are however ill understood. Our goal is to quantify these effects using data from the National Surveillance Study of Nosocomial Infections in Intensive Care

Units (Belgium). This is a challenging problem because of the presence of time-dependent confounders (such as exposure to mechanical ventilation)which lie on the causal path from infection to mortality. Standard statistical analyses may be severely misleading in such settings …

Infant Feeding Decisions Among Pregnant Black Wic Participants And The Role Of Peer Support, Astrid D. Mickens

Loma Linda University Electronic Theses, Dissertations & Projects

The purpose of this study was to identify the important factors that impact infant feeding decisions among Black women, and to determine whether peer support influences the relationship among theoretical constructs of the social learning theory. A convenience sample of 110 Black pregnant women, ages 18-45, attending Women, Infant and Children (WIC) clinics throughout Riverside and San Bernardino Counties were recruited to participate in the study through the Nutrition Services Department. Eligible participants included pregnant Black WIC clients in any stage of pregnancy.

The survey questions contained information about perceived support, cognitive knowledge, abilities and beliefs regarding breastfeeding. The goal …

The Expression Of Microrna Mir-107 Decreases Early In Alzheimer's Disease And May Accelerate Disease Progression Through Regulation Of Β-Site Amyloid Precursor Protein-Cleaving Enzyme 1, Wang-Xia Wang, Bernard W. Rajeev, Arnold J. Stromberg, Na Ren, Guiliang Tang, Qingwei Huang, Isidore Rigoutsos, Peter T. Nelson

Sanders-Brown Center on Aging Faculty Publications

MicroRNAs (miRNAs) are small regulatory RNAs that participate in posttranscriptional gene regulation in a sequence-specific manner. However, little is understood about the role(s) of miRNAs in Alzheimer's disease (AD). We used miRNA expression microarrays on RNA extracted from human brain tissue from the University of Kentucky Alzheimer's Disease Center Brain Bank with near-optimal clinicopathological correlation. Cases were separated into four groups: elderly nondemented with negligible AD-type pathology, nondemented with incipient AD pathology, mild cognitive impairment (MCI) with moderate AD pathology, and AD. Among the AD-related miRNA expression changes, miR-107 was exceptional because miR-107 levels decreased significantly even in patients with …

Estimation Of Controlled Direct Effects, Sylvie Goetgeluk, Stijn Vansteelandt, Els Goetghebeur

Harvard University Biostatistics Working Paper Series

No abstract provided.

A Comparison Of Different Methods For Predicting Cancer Mortality Counts At The State Level, Corinne Wilson

Virginia Journal of Science

Cancer is a major health issue in the United States. Reliable estimates of yearly cancer mortality counts are essential for resourcing and planning. The American Cancer Society has used several methods of forecasting to estimate the future cancer burden and researchers are continually working to develop new methods with improved performance. There have been studies comparing different models for predicting the US cancer mortality counts. This study explores and compares several different models for cancer mortality count predictions at the state level, principally for the state of Virginia. Results of the comparisons appear to show the final improved model to …

On Matched Pairs Sign Test Using Bivariate Ranked Set Sampling: An Application To Environmental Issues, Hani M. Samawi, Mohammad F. Al-Saleh, Obaid Al-Saidy

Biostatistics: Faculty Publications

The matched pairs sign test using bivariate ranked set sampling (BVRSS) is introduced and investigated. We show that this test is asymptotically more efficient than its counterpart sign test based on a bivariate simple random sample (BVSRS). The asymptotic null distribution and the efficiency of the test are derived. The Pitman asymptotic relative efficiency is used to compare the asymptotic performance of the matched pairs sign test using BVRSS versus using BVSRS. For small sample sizes, the bootstrap method is used to estimate P-values. Numerical comparisons are used to gain insight about the efficiency of the BVRSS sign test compared …

Efficacy Of Cognitive Therapy And Pharmacotherapy In Depression: A Meta-Analysis, Daniel B. Michel

Loma Linda University Electronic Theses, Dissertations & Projects

A meta-analysis comparing the long-term effectiveness of cognitive behavioral therapy (CBT) and pharmacotherapy in preventing relapse following treatment discontinuation was performed using published studies of depressed participants. Twenty-three articles met inclusionary criteria and were included in the analyses. Weighted effect sizes and moderators, treatment type, were calculated using statistical analysis software. Initially, fixed effects models were applied to the data, but due to significant between-group heterogeneity that could not be fully explained by treatment type, mixed effect models were used to account for the residual heterogeneity. Results indicated that overall, depressed individuals treated to remission with CBT evidence decreased relapse …

Immediate Implant Placement In Extraction Sites With Periapical Lesions: A Retrospective Study, Yuan-Lung Hung

Loma Linda University Electronic Theses, Dissertations & Projects

Immediate implant placement into fresh extraction sites has become a relatively routine clinical procedure with a favorable prognosis. However, immediate placement into extraction sockets with lesions has not been extensively documented in humans. Therefore, the purpose of this study was to retrospectively determine the survival rate of implants placed into extraction sockets with visible periapical lesions.

Patient charts of 544 immediately placed implants from Loma Linda University School of Dentistry, Center for Prosthodontics and Implant Dentistry were examined. Eighty-six of the 544 implants had been placed immediately into extraction sockets with periapical lesions and they were included in this study. …

Inference On Overlapping Coefficients In Two Exponential Populations, Mohammad F. Al-Saleh, Hani M. Samawi

Biostatistics: Faculty Publications

Three measures of overlap, namely Matusita’s measureρ , Morisita’s measure λ and Weitzman’s measure Δ are investigated in this article for two exponential populations with different means. It is well that the estimators of those measures of overlap are biased. The bias is of these estimators depends on the unknown overlap parameters. There are no closed-form, exact formulas, for those estimators variances or their exact sampling distributions. Monte Carlo evaluations are used to study the bias and precision of the proposed overlap measures. Bootstrap method and Taylor series approximation are used to construct confidence intervals for the overlap measures.

Correcting Instrumental Variables Estimators For Systematic Measurement Error, Stijn Vansteelandt, Manoochehr Babanezhad, Els Goetghebeur

Harvard University Biostatistics Working Paper Series

No abstract provided.

Predictors Of Emotional Reactions In Women Treated For Breast Cancer, Erin E. Ramirez

Loma Linda University Electronic Theses, Dissertations & Projects

Breast cancer can be a devastating disease that impacts a woman in all spheres of her life (Ingram, 1989). Previous studies have examined the impact of breast cancer on body satisfaction, as well as the impact on emotional well-being. Studies have also examined the role of the coping style that a woman engages in response to the diagnosis and treatment of breast cancer in the woman's psychological adjustment to the disease. However, to date, no research has introduced and tested a multifaceted model.

The purpose of this study was to develop a model predicting psychological maladjustment in women treated for …

Predictors Of Female Sexual Dysfunction, Julie M. Merrell

Loma Linda University Electronic Theses, Dissertations & Projects

Tiefer, Hall, and Tavris (2002) described factors comprising four categories of female sexual dysfunction. They suggested that unique factors need to be examined to understand sexual dysfunction in women. Socio-cultural, political, or economic factors, partner and relationship factors, psychological factors, and medical factors described as aspects of women’s lives that can be the source of sexual dysfunction. The current study examined indicators of the above factors-body shame, relationship satisfaction, sexual self-schema, positive and negative affect, and overall health-as predictors of female sexual dysfunction. The hypotheses were: Body shame and negative affect will be negatively associated with sexual function; and relationship …

Empirical Efficiency Maximization, Daniel B. Rubin, Mark J. Van Der Laan

U.C. Berkeley Division of Biostatistics Working Paper Series

It has long been recognized that covariate adjustment can increase precision, even when it is not strictly necessary. The phenomenon is particularly emphasized in clinical trials, whether using continuous, categorical, or censored time-to-event outcomes. Adjustment is often straightforward when a discrete covariate partitions the sample into a handful of strata, but becomes more involved when modern studies collect copious amounts of baseline information on each subject.

The dilemma helped motivate locally efficient estimation for coarsened data structures, as surveyed in the books of van der Laan and Robins (2003) and Tsiatis (2006). Here one fits a relatively small working model …

Incidence, Patterns And Severity Of Reported Unintentional Injuries In Pakistan For Persons Five Years And Older: Results Of The National Health Survey Of Pakistan 1990–94, Zafar Fatmi, Wilbur C. Hadden, Junaid A. Razzak, Huma Qureshi, Adnan A. Hyder, Gregory Pappas

Community Health Sciences

Background

National level estimates of injuries are not readily available for developing countries. This study estimated the annual incidence, patterns and severity of unintentional injuries among persons over five years of age in Pakistan.

Methods

National Health Survey of Pakistan (NHSP 1990–94) is a nationally representative survey of the household. Through a two-stage stratified design, 18, 315 persons over 5 years of age were interviewed to estimate the overall annual incidence, patterns and severity of unintentional injuries for males and females in urban and rural areas over the preceding one year. Weighted estimates were computed adjusting for complex survey design …

Identifying Patients Who Need Additional Biomarkers For Better Prediction Of Health Outcome Or Diagnosis Of Clinical Phenotype, Lu Tian, Tianxi Cai, L. J. Wei

Harvard University Biostatistics Working Paper Series

No abstract provided.

Salivary Characteristics In 3 And 4 Year-Old Children With And Without Visible Caries, Gloria Yañez

Loma Linda University Electronic Theses, Dissertations & Projects

PURPOSE: To compare salivary characteristics in 3 and 4 year-old Head Start children with and without visible caries.

METHODS: This case-control study was performed on 84 healthy 3 and 4 year-old Head Start children. After consent and inclusion criteria were met, each child was screened and assigned to one of two test groups based on their caries status. Group 1 consisted of children with no visible evidence of caries, although non-visible caries may have been present. Group II consisted of children with visible evidence demonstrating three or more carious lesions. Each child's unstimulated and stimulated whole saliva samples were collected …

Comparison Of Laser And Phosphoric Acid Etching On Sealant Shear Bond Strength, Seth David Latimer

Loma Linda University Electronic Theses, Dissertations & Projects

PURPOSE: To compare the effect of traditional phosphoric acid etching with Er,Cr:YSGG laser enamel etching on the shear bond strength of sealant material.

METHODS: Extracted healthy third molars were mounted in acrylic exposing the flattest surface available. Three groups of twenty teeth were used to evaluate traditional acid etching with 37% phosphoric acid as a control group as well as two different laser settings. The sealant material was attached using specialized jigs and then subjected to shear bond strength testing utilizing the ultradent method (MTS machine). Statistical methods employed were the Kruskal-Wallis rank test and the Mann-Whitney U test.

RESULTS: …

Adjusting For Covariates In Studies Of Diagnostic, Screening, Or Prognostic Markers: An Old Concept In A New Setting, Holly Janes, Margaret Pepe

UW Biostatistics Working Paper Series

The concept of covariate adjustment is well established in therapeutic and etiologic studies. However, it has received little attention in the growing area of medical research devoted to the development of markers for disease diagnosis, screening, or prognosis, where classification accuracy, rather than association, is of primary interest. In this paper, we demonstrate the need for covariate adjustment in studies of classification accuracy, discuss methods for adjusting for covariates, and distinguish covariate adjustment from several other related but fundamentally different uses for covariates. We draw analogies and contrasts throughout with studies of association.