Open Access. Powered by Scholars. Published by Universities.®

Digital Commons Network™

Open Access. Powered by Scholars. Published by Universities.®

Public Health

Institution
Keyword
Publication Year
Publication
Publication Type
File Type

Articles 46531 - 46560 of 55724

Full-Text Articles in Entire DC Network

Sexual Risk Behavior Among African-American Adolescents: Trajectories And Their Predictors, Maureen Muchimba Jan 2010

Sexual Risk Behavior Among African-American Adolescents: Trajectories And Their Predictors, Maureen Muchimba

All ETDs from UAB

Although adolescents in the United States are at high risk of sexually transmitted infections and HIV, research indicates that many do not use condoms consistently and have high numbers of lifetime multiple sexual partners. Among adolescents, different subgroups exhibit distinct patterns of sexual behavior over time. The purpose of this dissertation was to identify trajectories of sexual risk behavior among adolescents and to determine individual, family and community factors that are predictive of membership to trajectory groups. Data were collected on sexual risk behavior among low-income African-American adolescents in Mobile County, Alabama. Gender-balanced subsamples of risky sex (N = 1294) …


Oral Lesions As Clinical Markers For Antiretroviral Therapy Failure In Hiv Patients, Irene M. Tamí-Maury Jan 2010

Oral Lesions As Clinical Markers For Antiretroviral Therapy Failure In Hiv Patients, Irene M. Tamí-Maury

All ETDs from UAB

The true nature of the association of oral lesions (OL) and gold standards of HIV progression, CD4+ T cell counts (CD4) and HIV-1 RNA viral load (VL), is not completely clear, especially when patients are on antiretroviral therapy (ART). Our aim was to assess the association between OL and virologic failure among HIV/AIDS patients on ART. We conducted a retrospective study of 744 HIV patients who entered care between 2000 and 2006 at the UAB 1917 Clinic. Data was collected for 2 years after enrollment. Prevalence of OL was 35.8%. Oropharyngeal candidiasis (OPC) was the most prevalent OL (74.9%). Among …


Investigation Of The Cese Framework For Viscous Flows, Balaji Shankar Venkatachari Jan 2010

Investigation Of The Cese Framework For Viscous Flows, Balaji Shankar Venkatachari

All ETDs from UAB

A transient viscous solver has been developed based on the novel space-time conser-vation element solution element (CESE) framework. Till date, the numerical accuracy of the CESE framework in modeling inviscid flow problems has been well documented, while very little work has been done in regards to modeling transient viscous flows. In this work, an attempt to fill that gap in literature was carried out by rigorously investigat-ing the numerical accuracy and computational performance of the CESE framework in simulating such flows. The study aims at gaining a deeper understanding on the numeri-cal accuracy and dissipation characteristics of the CESE framework, …


Development And Validation Of A Scale To Measure Fear Of Physical Response To Exercise Among Overweight And Obese Adults, Brooks Cotton Wingo Jan 2010

Development And Validation Of A Scale To Measure Fear Of Physical Response To Exercise Among Overweight And Obese Adults, Brooks Cotton Wingo

All ETDs from UAB

specified and alteration of both Type I and Type II error rates occurs. We examine


Association Between Birth Outcomes And Aflatoxin B1-Biomarker Levels Among Pregnant Women In Kumasi, Ghana, Faisal Mohammed Barbas Shuaib Jan 2010

Association Between Birth Outcomes And Aflatoxin B1-Biomarker Levels Among Pregnant Women In Kumasi, Ghana, Faisal Mohammed Barbas Shuaib

All ETDs from UAB

Aflatoxins are fungal metabolites that contaminate staple food crops in many developing countries. Although studies have linked these toxins to adverse health outcomes, few studies have investigated the association between birth outcomes and aflatoxin B1-lysine adduct levels among pregnant women. The objective of this dissertation was to investigate the association between birth outcomes and aflatoxin B1- lysine adduct levels among pregnant women in Kumasi, Ghana. In a cross-sectional study of 755 pregnant women, Aflatoxin B1-lysine adduct (AF-ALB) levels were determined by High Performance Liquid Chromatography. AF-ALB associations were assessed as both continuous and categorical values. Analysis of variance (ANOVA) was …


Hypothesis Testing Based On Pool Screening With Unequal Pool Sizes, Hongjiang Gao Jan 2010

Hypothesis Testing Based On Pool Screening With Unequal Pool Sizes, Hongjiang Gao

All ETDs from UAB

Pool screening is a widely applied technique to estimate the prevalence of a rare event. This focus of this research is on developing statistical test of hypothesis procedures under the assumption that pool sizes are unequal but known. One of the proposed test procedures is , an exact test based on the number of positive pools (denoted by T). Another set of proposed test procedures is a modification of the likelihood ratio, Wald's and Score tests which are commonly-used likelihood-based tests. In paper 1, we derive the distribution of T which will be the basis of the exact test. Other …


Chronic Alcohol Consumption Promotes Opening Of The Mitochondrial Permeability Transition Pore And Increases Mitochondrial Injury In Liver, Adrienne Lester King Jan 2010

Chronic Alcohol Consumption Promotes Opening Of The Mitochondrial Permeability Transition Pore And Increases Mitochondrial Injury In Liver, Adrienne Lester King

All ETDs from UAB

Alcoholic liver disease is a serious public health concern. In particular, the mitochondrion is a specific target of ethanol toxicity and much of the damage can be related to unregulated Ca2+ homeostasis and oxidative stress which are key players in the induction of the mitochondrial permeability transition pore (MPTP) within the organelle. The mechanism behind the induction of the MPTP remains elusive. Therefore, this body of work will provide insight on what effects chronic alcohol consumption has on mitochondrial dysfunction with an emphasis on the MPTP. Chapter 2: Assessment of mitochondrial dysfunction arising from treatment with hepatotoxicants provides a description …


The Effects Of Paternal Absence On The Sexual Behaviors Of African-American Adolescents Living In Impoverished Neighborhoods, Cheri Nicolette Langley Jan 2010

The Effects Of Paternal Absence On The Sexual Behaviors Of African-American Adolescents Living In Impoverished Neighborhoods, Cheri Nicolette Langley

All ETDs from UAB

According to the 2005 Youth Risk Behavior Survey (YRBS), 47% of the surveyed high school students reported ever having sexual intercourse, with 6% reporting having initiated their first sexual intercourse before the age of 13 (Eaton et al., 2006). Using the Mobile Youth Survey (1998-2008), the purpose of this study is four-fold: (a) to describe the MYS sample (1998-2008) in terms of its primary independent variable (the absence of a father figure) and its primary outcomes (sexual debut, sexual frequency, number of sex partners, condom use, pregnancy in the last year, and pregnancy intention); (b) to determine the impact of …


Intimate Partner Violence Among Latinas In Central Alabama: Sociodemographic Characteristics, Perceptions Of Abuse, And Help-Seeking Behaviors, Angela Boy Jan 2010

Intimate Partner Violence Among Latinas In Central Alabama: Sociodemographic Characteristics, Perceptions Of Abuse, And Help-Seeking Behaviors, Angela Boy

All ETDs from UAB

This study utilized a cross-sectional design to survey 272 Latinas in the Birmingham metropolitan area and interview 29 Latinas who were known victims of IPV in the community. Prevalence, socio-demographic characteristics, perceptions of abuse, and help-seeking behaviors were examined, and the psychometric properties of the Woman Abuse Screening Tool (WAST) were assessed. Survey findings indicated current and lifetime IPV prevalence rates of 39.4% and 44.9%, respectively, among women aged 19-55. Victims were 1.9 times more likely to have been born in Central/South America than non-victims. Survey respondents had an average score of 32.5 (range 11-44) on the Perceptions of Abuse …


Determinants Of Self-Efficacy To Seek Care For Tuberculosis And Complete Tuberculosis Treatment Among Hiv-Positive Patients Attending Government Hiv/Aids Clincis In Honduras, Mayra Silvana Arias Jan 2010

Determinants Of Self-Efficacy To Seek Care For Tuberculosis And Complete Tuberculosis Treatment Among Hiv-Positive Patients Attending Government Hiv/Aids Clincis In Honduras, Mayra Silvana Arias

All ETDs from UAB

control


Host Preference Profile In An Area Of Eastern Equine Encephalitis (Eee) Virus Transmission In Alabama, Ana Lucia Oliveira Jan 2010

Host Preference Profile In An Area Of Eastern Equine Encephalitis (Eee) Virus Transmission In Alabama, Ana Lucia Oliveira

All ETDs from UAB

osteoporosis susceptibility, perceived osteoporosis severity, perceived barriers to


Radiographic Damage And Functional Disability In African American Patients With Recent-Onset Rheumatoid Arthritis, Jie Zhang Jan 2010

Radiographic Damage And Functional Disability In African American Patients With Recent-Onset Rheumatoid Arthritis, Jie Zhang

All ETDs from UAB

we adjust for heterskedasticity using a HCCM estimator, we find no significant evidence


Cancer In Louisiana: 2002-2006, Volume 24, Louisiana Tumor Registry, Patricia A. Andrews, Mei-Chin Hsieh, Brent Mumphrey, Lisa Pareti, Mary Namiak, Beth A. Schmidt, Edward S. Peters, Xiao-Cheng Wu, Vivien W. Chen Jan 2010

Cancer In Louisiana: 2002-2006, Volume 24, Louisiana Tumor Registry, Patricia A. Andrews, Mei-Chin Hsieh, Brent Mumphrey, Lisa Pareti, Mary Namiak, Beth A. Schmidt, Edward S. Peters, Xiao-Cheng Wu, Vivien W. Chen

Policy & Position Papers

Mission:

To collect and report complete, high-quality, and timely population-based cancer data in Louisiana to support cancer research, control, and prevention.

Vision:

To reduce suffering and death from cancer using information collected by the Louisiana Tumor Registry.

History:

Cancer registration in Louisiana began in 1947 at the Charity Hospital Tumor Registry in New Orleans. In 1974, as part of its Surveillance, Epidemiology and End Results (SEER) Program, the National Cancer Institute provided funds for a population-based cancer incidence and survival registry covering Jefferson, Orleans, and St. Bernard parishes. Five years later, the Louisiana Tumor Registry (LTR) was transferred to the …


Communalism Predicts Prenatal Affect, Stress, And Physiology Better Than Ethnicity And Socioeconomic Status, Cleopatra M. Abdou, Christine Dunkel Schetter, Belinda Campos, Clayton J. Hilmert, Tyan Parker Dominguez, Calvin J. Hobel, Laura M. Glynn, Curt A. Sandman Jan 2010

Communalism Predicts Prenatal Affect, Stress, And Physiology Better Than Ethnicity And Socioeconomic Status, Cleopatra M. Abdou, Christine Dunkel Schetter, Belinda Campos, Clayton J. Hilmert, Tyan Parker Dominguez, Calvin J. Hobel, Laura M. Glynn, Curt A. Sandman

Psychology Faculty Articles and Research

The authors examined the relevance of communalism, operationalized as a cultural orientation emphasizing interdependence, to maternal prenatal emotional health and physiology and distinguished its effects from those of ethnicity and childhood and adult socioeconomic status (SES). African American and European American women (N = 297) were recruited early in pregnancy and followed through 32 weeks gestation using interviews and medical chart review. Overall, African American women and women of lower socioeconomic backgrounds had higher levels of negative affect, stress, and blood pressure, but these ethnic and socioeconomic disparities were not observed among women higher in communalism. Hierarchical multivariate regression analyses …


Racial /Ethnic Disparities In Hypertension In United States Residents: A Cross-Sectional Study Of Potential Explanatory Covariates, Franklin I. Opara Jan 2010

Racial /Ethnic Disparities In Hypertension In United States Residents: A Cross-Sectional Study Of Potential Explanatory Covariates, Franklin I. Opara

Walden Dissertations and Doctoral Studies

Racial/ethnic disparities persist in hypertension (HTN) prevalence in the United States, and African Americans are disproportionately affected. The incidence is more than two-folds in African Americans compared to Caucasians, and mortality is highest among African Americans. Understanding the risk factors in HTN and how these factors vary across racial/ethnic groups is essential to reducing the mortality among African Americans. This study examined the prevalence of HTN among a sample non-institutionalized U.S. residents (N = 30,852), assessed racial/ethnic disparities and determined factors associated with racial/ethnic variance in HTN. A cross-sectional design was used to address these aims, utilizing the National Health …


The Effect Of Breastfeeding On The Bmi Of Hispanic Preschool Children, Linda M. Kilby Jan 2010

The Effect Of Breastfeeding On The Bmi Of Hispanic Preschool Children, Linda M. Kilby

Walden Dissertations and Doctoral Studies

The American Academy of Pediatrics and World Health Organization recommend exclusive breastfeeding for the first 4-6 months of life to reduce risk of obesity in pre-school children. Previous research has indicated a high rate of obesity among Hispanic children in the northeastern United States. There is also a gap in the literature regarding the effectiveness of exclusive breastfeeding in preventing obesity among preschool Hispanic children. Therefore, the purpose of this study was to determine if there was an association between exclusive breastfeeding and obesity among pre-school Hispanic children enrolled in the Special Supplemental Nutrition Education Program for Women, Infants and …


Social Capital Variables As Predictors Of Hiv Risk-Taking Behaviors Among Sub-Saharan African Immigrants In The United States, Gbadebo Ogundiran Ogungbade Jan 2010

Social Capital Variables As Predictors Of Hiv Risk-Taking Behaviors Among Sub-Saharan African Immigrants In The United States, Gbadebo Ogundiran Ogungbade

Walden Dissertations and Doctoral Studies

Vulnerable populations, including immigrants, are often at risk for human immunodeficiency virus (HIV) infection because of their risk-taking behaviors. This study investigated risk-taking behavior for HIV infection among Sub-Saharan African (SSA) immigrants in United States. Using social capital as a theoretical foundation, the study aimed to address the question, is there any association between social capital assets of educational opportunity, employment, and eligibility for social assistance and HIV risk-taking behavior, defined as condom use before sex (CUBS) among SSA immigrant in the U.S? Potential participants were recruited through religious and social organizations in a southwestern US state. The survey generated …


Utilizing The School Health Index To Foster University And Community Engagement., Kristi Mcclary King Jan 2010

Utilizing The School Health Index To Foster University And Community Engagement., Kristi Mcclary King

Faculty and Staff Scholarship

A Coordinated School Health Program maximizes a school’s positive interaction among health education, physical education, health services, nutrition services, counseling/psychological/social services, health school environment, health promotion for staff, and family and community involvement. The purpose of this semester project is for undergraduate health education students to (1) explain the Coordinated School Health Program, (2) assess local schools’ health programs and policies using the School Health Index, (3) develop a School Health Improvement Plan, and (4) present their findings and recommendations for improving their schools’ physical activity, nutrition, tobacco prevention, asthma, and safety policies and programs.


The Role Of Socioeconomic Factors In Racial And Ethnic Disparities Among Child And Adult Tuberculosis Cases, Spatial And Non-Spatial Analysis: Alabama 1993-2007, Sharada Adolph Jan 2010

The Role Of Socioeconomic Factors In Racial And Ethnic Disparities Among Child And Adult Tuberculosis Cases, Spatial And Non-Spatial Analysis: Alabama 1993-2007, Sharada Adolph

All ETDs from UAB

This study aimed to evaluate the role of individual and community/population level socioeconomic factors on racial/ethnic disparities among children and adults with TB, and used area-based socioeconomic measures (ABSMs) for the identification of high-risk geographic areas for populations-at-risk. Joinpoint, multivariable and Poisson regression, and spatial methods were used to determine the trends and risks of disease in a low TB incidence state. General disease trends declined significantly by factors of -0.044838 from 1993-1998, and -0.061821 from 2001-2007; but, were disparate and increased for the foreign-born, African Americans (AA) and Latinos, and in long-term care settings. The average annual percentage change …


Examining The Association Between Body Mass Index And Weight Related Quality Of Life In Black And White Women, Tiffany Lashaun Cox Jan 2010

Examining The Association Between Body Mass Index And Weight Related Quality Of Life In Black And White Women, Tiffany Lashaun Cox

All ETDs from UAB

Obesity not only increases risk for morbidity/mortality, but also impacts the quality of life of obese individuals. In the United States, black women have the highest prevalence of obesity of any other group with approximately 80% of black women over age 20 having a body mass index (BMI) ≥ 25 kg/m2. We aimed to examine the association between weight and quality of life in this high risk population and compare it to weight-related quality of life in white women using the Impact of Weight on Quality of Life (IWQOL)-Lite questionnaire. Data for 343 women were analyzed (172 black, 171 white). …


Evaluations Of Clinical Signs Currently And Not Currently Used In Syndromic Case Management (Scm) Of Reproductive Tract Infections (Rtis) Among Pregnant Women In Jamaica, Gelen Receno Del Rosario Jan 2010

Evaluations Of Clinical Signs Currently And Not Currently Used In Syndromic Case Management (Scm) Of Reproductive Tract Infections (Rtis) Among Pregnant Women In Jamaica, Gelen Receno Del Rosario

All ETDs from UAB

Reproductive tract infections include sexually transmitted infections, endogenous infections caused by overgrowth of organisms that can be present in the genital tract of a healthy woman, and iatrogenic infections. In Jamaica, women in the reproductive age group of 15-44 years old accounts for 95% of all RTIs. RTIs among Jamaican women of reproductive age can seriously impact the health of the women and their children. The advent of HIV/AIDS has had a significant impact on increasing awareness of the effect of STIs. Health care organizations have reacted with great commit-ment to STI prevention and treatment as a significant factor in …


Sense Of Community Among Adolescents Participating In The Mobile Youth Survey: A Measurement Study, Randolph Stacer Devereaux Jan 2010

Sense Of Community Among Adolescents Participating In The Mobile Youth Survey: A Measurement Study, Randolph Stacer Devereaux

All ETDs from UAB

A measurement study was conducted to evaluate 11 items representing the latent variable labeled "sense of community" (SOC) employed by investigators of the Mobile Youth Survey (MYS). In previous research the 11 items representing the concept of SOC have been combined to form a composite variable, assuming that the concept was best represented by a single factor (e.g., Bolland, Bryant, Lian, McCallum, Vazsonyi & Barth, 2007). However, no systematic analysis has been conducted to determine the psychometric properties of the 11-item composite variable. The objects of the present study are a) to determine the component structure of the items used …


Methods For Estimating Mediation Effect In Survival Analysis: Does Weight Loss Mediate The Undernutrition-Mortality Relationship In The Older Adults?, Yanhui Sun Jan 2010

Methods For Estimating Mediation Effect In Survival Analysis: Does Weight Loss Mediate The Undernutrition-Mortality Relationship In The Older Adults?, Yanhui Sun

All ETDs from UAB

The influence of undernutrition on mortality and other adverse outcomes through the mechanism of unintentional weight loss in older adults is often assumed, but the analytic methods to test these mediation mechanisms are not well-developed, and the need for methodological advances in this area motivated this program of research. We first examined the test-retest reliability and predictive validity of self-reported caloric intake as a measure of undernutrition. Acceptable reliability was observed, consistent with previous reports, but the evidence for predictive validity was inconsistent and self-reported caloric intake deficiency was not found to be related to observed weight loss. We then …


A Comparative Study Of Radiological Threat Environments And Radiation Control, Lisa C. Mccormick Jan 2010

A Comparative Study Of Radiological Threat Environments And Radiation Control, Lisa C. Mccormick

All ETDs from UAB

Radiation Control Programs (RCPs) differ from state to state as does their integration with public health agencies. The purpose of this study was threefold: to describe and compare across states the environmental radiological attributes of RCPs, to describe how these programs are organized structurally within state government, and to identify if RCPs differ structurally in environments of differing radiological attributes. Publicly available information from the Nuclear Regulatory Commission and state agency websites was used to determine both the environmental attributes and the different approaches states use to organize RCPs. States were grouped based on environmental attributes by employing a principle …


Therapeutic Interventions For Chlorine Gas Induced Lung Injury, Amit Kumar Yadav Jan 2010

Therapeutic Interventions For Chlorine Gas Induced Lung Injury, Amit Kumar Yadav

All ETDs from UAB

Rationale: Nitrite (NO2-) has been shown to limit injury to the heart, liver and kidneys in various models of ischemia-reperfusion injury. Currently, potential protective effects of systemic NO2- in limiting lung injury or enhancing repair have not been documented. Objectives: To assess the efficacy and mechanisms by which post-exposure intra-peritoneal injections of NO2- mitigate Cl2 induced lung injury in rats. Methods: Rats were exposed to Cl2 (400 ppm) for 30 minutes and returned to room air. Nitrite (1mg/Kg) or saline were administered intraperitoneally at 10 min, 2, 4 and 6 hrs post exposure. Rats were sacrificed at 6 hrs or …


A Pilot Study For A Computer-Tailored Program To Increase Calcium And Vitamin D Consumption In Young Women: Does Adding Quantitative Ultrasound Change Outcomes?, Donald Henry Lein Jan 2010

A Pilot Study For A Computer-Tailored Program To Increase Calcium And Vitamin D Consumption In Young Women: Does Adding Quantitative Ultrasound Change Outcomes?, Donald Henry Lein

All ETDs from UAB

Osteoporosis and osteoporosis-related fractures are costly personal and national problems. No cure exists so experts stress early practice of bone protective behaviors, like adequate calcium and vitamin D intake, to prevent osteoporosis and osteoporosis-related fractures. However, young women in the United States do not consume adequate amounts of these two nutrients. Further evaluation to identify cost effective programs to increase calcium and vitamin D consumption in young women is needed. The purpose of this study was to evaluate whether quantitative ultrasound (QUS) with bone strength feedback to a computer-tailored feedback and counseling intervention was needed to increase calcium and vitamin …


Fertility Enhancing Drugs, Assisted Reproductive Technologies And Effects On Maternal And Infant Outcomes Among Live Births In Texas, Suzanne Jay Roseman Jan 2010

Fertility Enhancing Drugs, Assisted Reproductive Technologies And Effects On Maternal And Infant Outcomes Among Live Births In Texas, Suzanne Jay Roseman

All ETDs from UAB

Most studies evaluating outcomes among infertility treatment users use a spontaneously conceived (SC) group for comparative purposes, despite obvious limitations to this approach. Further, lack of comprehensive U.S. data-sources recording infertility treatments, especially non-assisted reproductive technology (non-ART) infertility treatments, has hampered the ability of U.S. researchers to explore the effects of a particular infertility treatment modality (for example ART) on maternal and infant outcomes while controlling for the effects of infertility itself. The present study makes use of the new data item: "Pregnancy resulted from infertility treatment," further categorized into ART and non-ART infertility treatments--from the 2003 revision of birth …


Awareness And Knowledge Of Hiv/Aids Among Female Indian University Students In South India And As Immigrants In The U.S.-Mexico Border Region, Thenral D. Mangadu Jan 2010

Awareness And Knowledge Of Hiv/Aids Among Female Indian University Students In South India And As Immigrants In The U.S.-Mexico Border Region, Thenral D. Mangadu

Open Access Theses & Dissertations

ABSTRACT

The prevention of HIV/AIDS is a major global public health goal. The Joint United Nations Programme on HIV and AIDS (UNAIDS) estimates that 33 million individuals are infected with HIV worldwide and over two million of these cases are from India. The main mode of transmission of HIV in India is heterosexual contact.

In the past decades there has been a steady increase in immigration rates from India to the U.S. Education and marriage are the main reasons for immigration from India to the U.S. In general, the frequently risky sexual and substance use behaviors of college students in …


The Latina/O Mental Health Paradox Or Racial/Ethnic Disparities? Depression Among New Immigrants To The U.S, Sandra Iveth Ramirez Jan 2010

The Latina/O Mental Health Paradox Or Racial/Ethnic Disparities? Depression Among New Immigrants To The U.S, Sandra Iveth Ramirez

Open Access Theses & Dissertations

The Latino/a Mental Health Paradox states that the foreign-born immigrants have better mental health outcomes when compared with native-born groups of various ethno-racial backgrounds, with the gap in mental stress minimizing overtime. The objective of this study is to examine whether Latina/os immigrants suffer an ethno-racial disparity in mental health or if they have favorable mental health outcomes as predicted by the Paradox. Expanding on the Latina/o Mental Health Paradox, rather than comparing Latina/o immigrants with native-born, this study will compare depression among recently legalized Latina/os with recent legalized European immigrants.


Identifying Influential Observations Through The Intraclass Correlation Coefficient, Angel De Jesus Davalos Jan 2010

Identifying Influential Observations Through The Intraclass Correlation Coefficient, Angel De Jesus Davalos

Open Access Theses & Dissertations

In this thesis, we analyze the performance of adapting the DFBETA statistic for identifying influential observations on the intraclass correlation coefficient under the assumptions of the one-way random effects model. Additionally, we introduce an approach for transforming negative intraclass correlation coefficient estimation values using the method of moments estimator. We apply this method on a data set of repeated blood pressure measurements, after which we will investigate implications of identifying influential observations.