Multivariate Analysis Commons^™

Relationship Of Vitamin D Levels To Blood Pressure In A Biethnic Cohort, Rosario O. Sakamoto

Loma Linda University Electronic Theses, Dissertations & Projects

Background: Serum hydroxyvitamin D [25(OH)D] has been well-accepted as not an ordinary vitamin but a pro-hormone that has many benefits beyond its well-known effects on bone. Cardiovascular risk factors such as hypertension remain a huge health burden and Blacks have been recognized to have higher prevalence of hypertension compared to non-Hispanic Whites. Despite increasing evidence of the benefits of vitamin D on blood pressure control, there is much more to be learned about the relationship of serum 25(OH)D to blood pressure among different ethnicities.

Purpose: The goal of this study was to determine whether vitamin D serum 25(OH)D levels were …

Effects Of Acculturation On Hiv/Aids Sexual Risk Behaviors Among Asian And Pacific Islander (Api) Women, Margaret Cabotage Salud

Loma Linda University Electronic Theses, Dissertations & Projects

Background. In the US women are the fastest growing group for sexually transmitted infections (STIs), including HIV and AIDS. In addition, the estimated AIDS cases among female adults and adolescents, aged 13-19, increased from 7% in 1985 to approximately 26% in 2002. Most infections occur by heterosexual transmission with 53% occurring through contact with a high-risk sexual partner. While overall HIV/AIDS rates in the Asian Pacific Islander (API) community remain low, they are rising and HIV testing rates, one of the major prevention strategies for HIV, are lower than that of other populations. Furthermore, very little is known about APIs …

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 …

The Prevalence And Determinants Of Health Risk Behaviors Among High School Students In Mexico, Nellie León

Loma Linda University Electronic Theses, Dissertations & Projects

The Centers for Disease Control and Prevention report that despite health promotion efforts, adolescents continue to engage in behaviors that put them at risk for morbidity and mortality. Alcohol consumption, illicit drug use, smoking, and risky sexual behaviors are among the behaviors that contribute to leading causes of morbidity and mortality in youth; these four behaviors were explored in this study. An observational cross-sectional design was utilized. The Youth Risk Behavior Survey from the Centers for Disease Control and Prevention was utilized to assess the prevalence of the four risk behaviors among high school students in Jalisco, Mexico. Items constructed …

The Influence Of Familism On Descriptive And Injunctive Norms In Predicting The Intention To Eat A Vegetarian Diet Among Chinese Seventh-Day Adventists, See Wei Toh

Loma Linda University Electronic Theses, Dissertations & Projects

According to the theory of planned behavior (TpB), one determinant of intention to engage in a behavior is the subjective norm. Various studies have found that subjective norm is often the weaker predictor of intention compared to perceived behavioral control and attitude. This study examined whether familism (emphasis on the family rather than the individual) would contribute positively to the predictive power of the TpB model through interactions with the family portion of descriptive and injunctive norms. Descriptive and injunctive norms are component variables of the subjective norm. A sample of 284 adult Chinese Seventh-day Adventists 18 years and older …

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 …

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 …

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 …

The Association Between Lifestyle Factors And Inflammatory Markers, Kerry Ann Stonebrook

Loma Linda University Electronic Theses, Dissertations & Projects

Background: Cardiovascular disease (CVD) is the leading cause of death for both men and women in the United States. While smoking, high blood pressure, and elevated cholesterol levels are established risk factors for CVD, inflammation is being evaluated as a potential independent risk factor. A key cytokine regulator of the inflammatory response, interleukin-1 (IL-1), has emerged as playing a particularly important role at the genetic level in determining the degree to which the inflammation pathway is turned on. How an individual’s genetic make-up affects inflammation, CVD risk, and response to lifestyle intervention is an area of research that is in …

Power Boosting In Genome-Wide Studies Via Methods For Multivariate Outcomes, Mary J. Emond

UW Biostatistics Working Paper Series

Whole-genome studies are becoming a mainstay of biomedical research. Examples include expression array experiments, comparative genomic hybridization analyses and large case-control studies for detecting polymorphism/disease associations. The tactic of applying a regression model to every locus to obtain test statistics is useful in such studies. However, this approach ignores potential correlation structure in the data that could be used to gain power, particularly when a Bonferroni correction is applied to adjust for multiple testing. In this article, we propose using regression techniques for misspecified multivariate outcomes to increase statistical power over independence-based modeling at each locus. Even when the outcome …

Semiparametric Regression Of Multi-Dimensional Genetic Pathway Data: Least Squares Kernel Machines And Linear Mixed Models, Dawei Liu, Xihong Lin, Debashis Ghosh

Harvard University Biostatistics Working Paper Series

No abstract provided.

Semiparametric Latent Variable Regression Models For Spatio-Temporal Modeling Of Mobile Source Particles In The Greater Boston Area, Alexandros Gryparis, Brent A. Coull, Joel Schwartz, Helen H. Suh

Harvard University Biostatistics Working Paper Series

Traffic particle concentrations show considerable spatial variability within a metropolitan area. We consider latent variable semiparametric regression models for modeling the spatial and temporal variability of black carbon and elemental carbon concentrations in the greater Boston area. Measurements of these pollutants, which are markers of traffic particles, were obtained from several individual exposure studies conducted at specific household locations as well as 15 ambient monitoring sites in the city. The models allow for both flexible, nonlinear effects of covariates and for unexplained spatial and temporal variability in exposure. In addition, the different individual exposure studies recorded different surrogates of traffic …

Causal Inference In Longitudinal Studies With History-Restricted Marginal Structural Models, Romain Neugebauer, Mark J. Van Der Laan, Ira B. Tager

U.C. Berkeley Division of Biostatistics Working Paper Series

Causal Inference based on Marginal Structural Models (MSMs) is particularly attractive to subject-matter investigators because MSM parameters provide explicit representations of causal effects. We introduce History-Restricted Marginal Structural Models (HRMSMs) for longitudinal data for the purpose of defining causal parameters which may often be better suited for Public Health research. This new class of MSMs allows investigators to analyze the causal effect of a treatment on an outcome based on a fixed, shorter and user-specified history of exposure compared to MSMs. By default, the latter represents the treatment causal effect of interest based on a treatment history defined by the …

Insights Into Latent Class Analysis, Margaret S. Pepe, Holly Janes

UW Biostatistics Working Paper Series

Latent class analysis is a popular statistical technique for estimating disease prevalence and test sensitivity and specificity. It is used when a gold standard assessment of disease is not available but results of multiple imperfect tests are. We derive analytic expressions for the parameter estimates in terms of the raw data, under the conditional independence assumption. These expressions indicate explicitly how observed two- and three-way associations between test results are used to infer disease prevalence and test operating characteristics. Although reasonable if the conditional independence model holds, the estimators have no basis when it fails. We therefore caution against using …

Standardizing Markers To Evaluate And Compare Their Performances, Margaret S. Pepe, Gary M. Longton

UW Biostatistics Working Paper Series

Introduction: Markers that purport to distinguish subjects with a condition from those without a condition must be evaluated rigorously for their classification accuracy. A single approach to statistically evaluating and comparing markers is not yet established.

Methods: We suggest a standardization that uses the marker distribution in unaffected subjects as a reference. For an affected subject with marker value Y, the standardized placement value is the proportion of unaffected subjects with marker values that exceed Y.

Results: We apply the standardization to two illustrative datasets. In patients with pancreatic cancer placement values calculated for the CA 19-9 marker are smaller …

Combining Predictors For Classification Using The Area Under The Roc Curve, Margaret S. Pepe, Tianxi Cai, Zheng Zhang, Gary M. Longton

UW Biostatistics Working Paper Series

No single biomarker for cancer is considered adequately sensitive and specific for cancer screening. It is expected that the results of multiple markers will need to be combined in order to yield adequately accurate classification. Typically the objective function that is optimized for combining markers is the likelihood function. In this paper we consider an alternative objective function -- the area under the empirical receiver operating characteristic curve (AUC). We note that it yields consistent estimates of parameters in a generalized linear model for the risk score but does not require specifying the link function. Like logistic regression it yields …

Combining Predictors For Classification Using The Area Under The Roc Curve, Margaret S. Pepe, Tianxi Cai, Zheng Zhang

UW Biostatistics Working Paper Series

We compare simple logistic regression with an alternative robust procedure for constructing linear predictors to be used for the two state classification task. Theoritical advantages of the robust procedure over logistic regression are: (i) although it assumes a generalized linear model for the dichotomous outcome variable, it does not require specification of the link function; (ii) it accommodates case-control designs even when the model is not logistic; and (iii) it yields sensible results even when the generalized linear model assumption fails to hold. Surprisingly, we find that the linear predictor derived from the logistic regression likelihood is very robust in …

Evaluating Markers For Selecting A Patient's Treatment, Xiao Song, Margaret S. Pepe

UW Biostatistics Working Paper Series

Selecting the best treatment for a patient's disease may be facilitated by evaluating clinical characteristics or biomarker measurements at diagnosis. We consider how to evaluate the potential of such measurements to impact on treatment selection algorithms. For example, magnetic resonance neurographic imaging is potentially useful for deciding whether a patient should be treated surgically for carpal tunnel syndrome or if he/she should receive less invasive conservative therapy. We propose a graphical display, the selection impact (SI) curve, that shows the population response rate as a function of treatment selection criteria based on the marker. The curve can be useful for …

Selecting Differentially Expressed Genes From Microarray Experiments, Margaret S. Pepe, Gary M. Longton, Garnet L. Anderson, Michel Schummer

UW Biostatistics Working Paper Series

High throughput technologies, such as gene expression arrays and protein mass spectrometry, allow one to simultaneously evaluate thousands of potential biomarkers that distinguish different tissue types. Of particular interest here is cancer versus normal organ tissues. We consider statistical methods to rank genes (or proteins) in regards to differential expression between tissues. Various statistical measures are considered and we argue that two measures related to the Receiver Operating Characteristic Curve are particularly suitable for this purpose. We also propose that sampling variability in the gene rankings be quantified and suggest using the “selection probability function”, the probability distribution of rankings …

Semi-Parametric Regression For The Area Under The Receiver Operating Characteristic Curve, Lori E. Dodd, Margaret S. Pepe

UW Biostatistics Working Paper Series

Medical advances continue to provide new and potentially better means for detecting disease. Such is true in cancer, for example, where biomarkers are sought for early detection and where improvements in imaging methods may pick up the initial functional and molecular changes associated with cancer development. In other binary classification tasks, computational algorithms such as Neural Networks, Support Vector Machines and Evolutionary Algorithms have been applied to areas as diverse as credit scoring, object recognition, and peptide-binding prediction. Before a classifier becomes an accepted technology, it must undergo rigorous evaluation to determine its ability to discriminate between states. Characterization of …

The Analysis Of Placement Values For Evaluating Discriminatory Measures, Margaret S. Pepe, Tianxi Cai

UW Biostatistics Working Paper Series

The idea of using measurements such as biomarkers, clinical data, or molecular biology assays for classification and prediction is popular in modern medicine. The scientific evaluation of such measures includes assessing the accuracy with which they predict the outcome of interest. Receiver operating characteristic curves are commonly used for evaluating the accuracy of diagnostic tests. They can be applied more broadly, indeed to any problem involving classification to two states or populations (D = 0 or D = 1). We show that the ROC curve can be interpreted as a cumulative distribution function for the discriminatory measure Y in the …

Risk Factors Associated With Infant Mortality Among Very Low Birthweight Infants Of Teenage Mothers In San Bernardino County, C. Letitia Henry

Loma Linda University Electronic Theses, Dissertations & Projects

Background. Typically, infant mortality decreases as maternal age increases in teenagers. In contrast to these national data, San Bernardino County (SBC) experienced a different phenomenon in 1989-1994 among very low birthweight (VLBW) infants. The infant mortality rate (IMR) of VLBW infants born to mothers under 17 years old (283 per 1000 live births) was significantly lower than the IMR of VLBW infants born to mothers between the ages of 17-19 years old (430 per 1000 live births) (p = .02).

Purpose. The purpose of the study was to explain the discrepancy between IMRs of VLBW infants of younger teenage mothers …

Methodological And Substantive Issues In Substance Abuse Prevention Research, C. Anderson Johnson, John W. Farquhar, Steve Sussman

CGU Faculty Publications and Research

This article summarizes current issues in drug abuse prevention research through integration of other articles in this journal and by heeding historical trends in prevention science. Recommendations are made for future research directions. For prevention to advance, iterative processes are needed involving both quasi-experimental and experimental designs and involving both small, simple units and large, complex, interactive units. Accuracy of measurement and replication are of paramount importance.

Correlates Of Birth Weight And Gestation Age : Baseline Data For Health Education, Adanetch Kidanemariam

Loma Linda University Electronic Theses, Dissertations & Projects

Purpose. The study examined the correlation of maternal occupation, urinary tract infection, smoking, and working during pregnancy with infant birth weight and gestational age in order to generate baseline data for development of a health education intervention program protocol for pregnant women In the work place.

Primary Hypotheses. (1) The four maternal risk factors: (a) occupation during lifetime, (b) reported urinary tract infection, (c) cigarette smoking, (d) working, are individually and interactively correlated with infant birth weight and gestational age. (2) The effects of the interactive associations are greater on birth weight than gestational age.

Procedure. A sample of …

The Effect Of Nursing Discharge Counseling Sessions On The Pre-Discharge Anxiety Level Of The Neurotically-Depressed Female In A Community Hospital Setting, Deborah Snyder Galasso

Loma Linda University Electronic Theses, Dissertations & Projects

Discharge from the hospital has been identified as a time when patients are in need of additional nursing support. The prospect of leaving the protective hospital environment to return to the home environment with its life stresses can cause anxiety. This study was designed to test the effect of a nursing intervention, discharge counseling sessions, on the anxiety level of the neurotically-depressed female prior to discharge.

The null hypothesis guiding this study was: nursing discharge counseling sessions will have no significant (α=0.05) effect on the pre-discharge anxiety level of the neurotically-depressed female in a community hospital setting. The State-Trait Anxiety …

Relationship Between Some Demographic Characteristics And Adverse Reactions Experienced By Women Undergoing A Therapeutic Abortion While Awake, Karen K. House

Loma Linda University Electronic Theses, Dissertations & Projects

With the liberalization of abortion laws by the Supreme Court in 1973, American women have been able to obtain therapeutic abortions in hospitals and out-patient clinics in ever increasing numbers. With the increased number of women seeking abortions the medical field has responded with abortion procedures that are safe and relatively quick. With the speed doctors use to perform the procedure, many women may wish to take advantage of the medically safer method of abortion under local anesthesia. However, some women are unable to withstand the psychological and physical stress associated with a therapeutic abortion while awake. It would be …

Using A Participating Relationship To Improve Teen-Age Unwed Mother's Self-Esteem, Linda Gail Reeves

Loma Linda University Electronic Theses, Dissertations & Projects

The study was to provide an approach to help teen-age unwed mothers increase their feelings of self-esteem and thereby attain a conceptual buffer for better coping with life. Self-esteem was defined as individual perception of the worth of oneself relative to that of significant others. The hypothesis tested was that the participating relationship a community health nurse has with a teen-age unwed mother will significantly increase the mother's self-esteem as measured by statistical Q-Sort analysis.

A convenience sample of twenty teen-age unwed mothers was obtained from referrals from San Bernardino County Health, Welfare, and Probation Departments. The girls were between …

Accidents Involving Nursing Service Personnel Reported During A Two-Year Period In A Selected General Hospital, Evelyn Helen Domke

Loma Linda University Electronic Theses, Dissertations & Projects

The study was conducted in an attempt to identify factors in the work situation which seemed to have had bearing on accidents involving nursing service employees, and to analyze and classify these factors for use in accident prevention and safety education activities. An accident was any sudden and unexpected event which resulted in a physical injury.

Literature was reviewed to study the findings of past studies in the area of hospital accidents, and to aid in the classification of the accident data which were applicable to nursing service personnel.

The descriptive survey method of research using the California State compensation …