Browsing by Subject "Regression analysis"
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Item Attachment Avoidance and Depressive Symptoms: A Test of Moderation by Cognitive Abilities(2014-09-04) Shea, Amanda Marie; Rand, Kevin L.; Stewart, Jesse C.; Cyders, Melissa A.; Ashburn-Nardo, Leslie; Grahame, Nicholas J.The substantial interpersonal and economic costs of depression make it imperative to better understand the predictors and moderators of depressive symptoms. The ability to use social support protects people from depressive symptoms, but individuals high in attachment avoidance tend not to use others as sources of support. Research has found that attachment avoidance is related to depressive symptoms in some samples but not in others (Mikulincer & Shaver, 2007; Shea, 2011). Thus, there appear to be factors that moderate the relationship between attachment avoidance and depressive symptoms. The present study examined if cognitive abilities that facilitate effective emotion regulation strategies moderate the relationship between attachment avoidance and depressive symptoms. Using a sample of college students, attachment avoidance, cognitive abilities, depressive symptoms, and other indices of psychological distress and well-being were measured and examined for evidence of moderation via hierarchical linear regression. The hypothesis that cognitive abilities moderate the relationship between attachment avoidance and depressive symptoms was not supported (ΔR2 = 0.02, p = .68). Factors contributing to the null findings are discussed and conceptual and methodological suggestions are offered for future research.Item Dietary intake and urinary excretion of phytoestrogens in relation to cancer and cardiovascular disease(2014) Reger, Michael Kent; Zollinger, Terrell; Jones, Josette F.; Liu, Ziyue; Zhang, JianjunPhytoestrogens that abound in soy products, legumes, and chickpeas can induce biologic responses in animals and humans due to structural similarity to 17β-estradiol. Although experimental studies suggest that phytoestrogen intake may alter the risk of cancer and cardiovascular disease, few epidemiologic studies have investigated this research question. This dissertation investigated the associations of intake of total and individual phytoestrogens and their urinary biomarkers with these chronic conditions using data previously collected from two US national cohort studies (NHANES and PLCO). Utilizing NHANES data with urinary phytoestrogen concentrations and follow-up mortality, Cox proportional hazards regression (HR; 95% CI) were performed to evaluate the association between total cancer, cardiovascular disease, and all-cause mortality and urinary phytoestrogens. After adjustment for confounders, it was found that higher concentrations of lignans were associated with a reduced risk of death from cardiovascular disease (0.48; 0.24-0.97), whereas higher concentrations of isoflavones (2.14; 1.03-4.47) and daidzein (2.05; 1.02-4.11) were associated with an increased risk. A reduction in all-cause mortality was observed for elevated concentrations of lignans (0.65; 0.43-0.96) and enterolactone (0.65; 0.44-0.97). Utilizing PLCO data and dietary phytoestrogens, Cox proportional hazards regression examined the associations between dietary phytoestrogens and the risk of prostate cancer incidence. After adjustment for confounders, a positive association was found between dietary intake of isoflavones (1.58; 1.11-2.24), genistein (1.42; 1.02-1.98), daidzein (1.62; 1.13-2.32), and glycitein (1.53; 1.09-2.15) and the risk of advanced prostate cancer. Conversely, an inverse association existed between dietary intake of genistein and the risk of non-advanced prostate cancer (0.88; 0.78-0.99) and total prostate cancer (0.90; 0.81-1.00). C-reactive protein (CRP) concentration levels rise in response to inflammation and higher levels are a risk factor for some cancers and cardiovascular disease reported in epidemiologic studies. Logistic regression performed on NHANES data evaluated the association between CRP and urinary phytoestrogen concentrations. Higher concentrations of total and individual phytoestrogens were associated with lower concentrations of CRP. In summary, dietary intake of some phytoestrogens significantly modulates prostate cancer risk and cardiovascular disease mortality. It is possible that these associations may be in part mediated through the influence of phytoestrogen intake on circulating levels of C-reactive protein.Item Factors in African American social work student persistence(2014-07-30) Green, Jacqualyn F.; Barton, William H., 1949-; Brown, O. Gilbert; Haas, Linda; Hull, Grafton H.; Smith, Linda A.Population estimations for the year 2000 indicate an increase in poor and minorities in the United States (Loden & Rosener, 1991). In view of this growth trend, Berger (1989) suggests a need for social workers with sensitivity to such populations. The presence of minority perspectives provides a valuable contribution to service delivery (Mullen et al., 1993). Efforts to enhance student persistence in graduate schools of social work will contribute to the pool of social workers available in the next century. The purpose of this study is to determine the factors that contribute to African American student persistence in graduate schools of social work. This study applies aspects of Astin's, Tinto's and Green's theories of persistence. Astin's theory of involvement (1975) considers student investment of time in educational pursuits. Tinto's (1975) theory of departure includes background, social and academic aspects in persistence decisions. Green's (1997) theory focuses on the ability of the student to cope with racial issues (racial resilience) and the racial climate of the school (racial responsiveness). One hundred and thirty-five students from two predominantly white and two historically black universities participated in surveys administered to determine the effect of involvement, background, academic, social, resilience factors, and college type upon student persistence outcomes. Interviews held with administrative personnel at each institution provided contextual data. Correlations were used to examine the relationships among all of the variables in the study. T-Tests were conducted to compare outcomes due to university type. Multiple regressions were used to explore the relationships between significant independent variables and persistence. The findings of this study indicate that persistence outcomes of African American graduate social work students are influenced by: (a) academic performance, faculty-student relationships, (c) health, (d) the ability to deal with stress, and (e) ethnic pride (impressions of ethnic group). These findings suggest that social work programs that incorporate aggressive grade monitoring practices, provide diverse opportunities for student-faculty interaction, offer opportunities for health care, stress alternatives, and a culturally relevant curriculum, may positively influence African American student persistence.Item Flexible models of time-varying exposures(2015-05) Wang, Chenkun; Gao, Sujuan; Liu, Hai; Yu, Zhangsheng; Callahan, Christopher M.With the availability of electronic medical records, medication dispensing data offers an unprecedented opportunity for researchers to explore complex relationships among longterm medication use, disease progression and potential side-effects in large patient populations. However, these data also pose challenges to existing statistical models because both medication exposure status and its intensity vary over time. This dissertation focused on flexible models to investigate the association between time-varying exposures and different types of outcomes. First, a penalized functional regression model was developed to estimate the effect of time-varying exposures on multivariate longitudinal outcomes. Second, for survival outcomes, a regression spline based model was proposed in the Cox proportional hazards (PH) framework to compare disease risk among different types of time-varying exposures. Finally, a penalized spline based Cox PH model with functional interaction terms was developed to estimate interaction effect between multiple medication classes. Data from a primary care patient cohort are used to illustrate the proposed approaches in determining the association between antidepressant use and various outcomes.Item Food attentional biases and adiposity: are energy intake and external eating mediators of this relationship?(2015-08) Vrany, Elizabeth; Stewart, Jesse C.; Cyders, Melissa Anne; Mosher, Catherine EstherObesity is a substantial threat to the health of over a third of adults in the United States. Some evidence suggests that food attentional bias, or the tendency to automatically direct attention toward food-related stimuli in the environment, may contribute to the development of obesity in susceptible individuals. This study hypothesized that (1) food attentional bias would be positively associated with adiposity, (2) food attentional bias would be positively associated with energy intake and external eating, and (3) energy intake and external eating would partially mediate the association between food attentional bias and adiposity. Data were collected from a sample of 120 undergraduate students. Three measures of food attentional bias were obtained: reaction time bias obtained from a visual dot-probe task and direction bias and duration bias obtained from eye tracking. Adiposity indices of body mass index (kg/m2) and body fat percent were measured using standard medical devices. Data were obtained for two mediators: 1) energy intake was assessed by web-based automated 24-hour dietary recall and 2) external eating was assessed using the External Eating Subscale of the Dutch Eating Behavior Questionnaire. Separate linear regression models examining the association between each measure of food attentional bias with each measure of adiposity (adjusted for age, sex, race/ethnicity, and subjective hunger) indicated no associations. Similarly, linear regression analyses revealed no associations between measures of food attentional bias and energy intake or external eating. Models testing for statistical mediation demonstrated that energy intake and external eating were not significant mediators. However, mediation analyses demonstrated a significant overall effect and direct effect between direction bias and BMI in a reduced sample used to test for energy intake as a mediator, suggesting the presence of an association which may not have been detected in the larger sample due to methodological issues, measurement error, or type I error. Despite the overall null results, these findings, in conjunction with previous studies on food attentional biases and adiposity, highlight the need for future investigations examining prospective associations between food attentional bias and adiposity.Item Investigating Predictors of Treatment Attrition Among Court-Ordered Batterers(The original doi for the final version of the article is 10.1300/J079v28n04_03. To access the doi, open the following DOI site in your browser and cut and paste the doi name where indicated: [LINK]http://dx.doi.org[/LINK]. [BREAK] Access to the original article may require subscription and authorized logon ID/password. IUPUI faculty/staff/students please check University Library resources before purchasing an article. Questions on finding the original article via our databases? Ask a librarian: [LINK] http://www.ulib.iupui.edu/research/askalibrarian [/LINK]., 2002) Buttell, Frederick P.; Pike, Cathy KingObjective: The purpose of this study was to investigate differences in demographic variables and psychological variables between treatment completers and drop-outs among abusive men entering a court-mandated treatment program. Method: The study gathered Domestic Violence Inventory (DVI) scores from 91 men, 66 treatment completers and 25 drop-outs, beginning court-ordered treatment for domestic violence offenses. Results: Logistic regression analyses indicated that none of the demographic variables or the psychological variables differentiated treatment completers from drop-outs. Conclusion: Implications of the findings for improving retention rates among men attending court-mandated batterer treatment programs were explored and discussed.Item Network-guided sparse learning for predicting cognitive outcomes from MRI measures(Springer, 2013) Yan, Jingwen; Huang, Heng; Risacher, Shannon L.; Kim, Sungeun; Inlow, Mark; Moore, Jason H.; Saykin, Andrew J.; Shen, Li; Department of Radiology and Imaging Sciences, School of MedicineAlzheimer's disease (AD) is characterized by gradual neurodegeneration and loss of brain function, especially for memory during early stages. Regression analysis has been widely applied to AD research to relate clinical and biomarker data such as predicting cognitive outcomes from MRI measures. In particular, sparse models have been proposed to identify the optimal imaging markers with high prediction power. However, the complex relationship among imaging markers are often overlooked or simplified in the existing methods. To address this issue, we present a new sparse learning method by introducing a novel network term to more flexibly model the relationship among imaging markers. The proposed algorithm is applied to the ADNI study for predicting cognitive outcomes using MRI scans. The effectiveness of our method is demonstrated by its improved prediction performance over several state-of-the-art competing methods and accurate identification of cognition-relevant imaging markers that are biologically meaningful.Item Posttraumatic stress disorder and chronic musculoskeletal pain : how are they related?(2014-07-11) Peng, Xiaomei; Bair, Matthew J.; Kroenke, Kurt; Faries, Douglas E.; Mac Kinnon, JoyceSymptoms of post-traumatic stress disorder (PTSD) are a common comorbidity in veterans seeking treatment of chronic musculoskeletal pain (CMP). However, little is known regarding the mutual influence of PTSD and CMP in this population. Using cross-sectional and longitudinal data from a randomized clinical trial evaluating a stepped care intervention for CMP in Iraq/Afghanistan veterans (ESCAPE), this dissertation examined the relationships between PTSD and CMP along with other factors including depression, anxiety, catastrophizing and health-related quality of life. The Classification and Regression Tree (CART) analysis was conducted to identify key factors associated with baseline PTSD besides CMP severity. A series of statistical analyses including logistical regression analysis, mixed model repeated measure analysis, confirmatory factor analysis and cross-lagged panel analysis via structural equation modeling were conducted to test five competing models of PTSD symptom clusters, and to examine the mutual influences of PTSD symptom clusters and CMP outcomes. Results showed baseline pain intensity and pain disability predicted PTSD at 9 months. And baseline PTSD predicted improvement of pain disability at 9 months. Moreover, direct relationships were found between PTSD and the disability component of CMP, and indirect relationships were found between PTSD, CMP and CMP components (intensity and disability) mediated by depression, anxiety and pain catastrophizing. Finally, the coexistence of PTSD and more severe pain was associated with worse SF-36 Physical Component Summary (PCS) and Mental Component Summary (MCS) scores. Together these findings provided empirical support for the mutual maintenance theory.Item The psychosocial outcomes of adult siblings of adults with autism and Down syndrome(2014-07-31) Belkin, Teri; McGrew, John H., 1953-; Mosher, Catherine E.; Johnson, Kathy E.; Grahame, Nicholas J.Little is known regarding the psychosocial outcomes of adult siblings of adults with autism. Accordingly, the current study sought to: (1) illuminate factors that predict health-related quality of life, caregiver burden, and reported benefits in adult siblings of adults with autism, using a stress and coping framework and (2) compare outcomes of siblings of adults with autism (n = 31) to siblings of adults with Down syndrome (DS) (n = 54). For the within subject hypotheses, analyses were repeated within the DS group and an overall Disability group (n = 97). The Disability group consisted of participants in the Autism and Down syndrome groups plus twelve individuals in a mixed group of adult siblings of adults with DS who presented with co-morbid symptoms of autism. Variables were organized using The Adult Sibling Caregiver Conceptual Model (ASCCM) into three categories: antecedents (e.g., sibling relationship quality, problem behaviors of the disabled sibling), mediators (e.g., coping strategies, cognitive appraisal types), and psychosocial outcome variables (i.e., mental and physical health-related quality of life, caregiver burden, and reported benefits). For the within subject primary hypotheses, I posited a series of relationships between the antecedents and outcomes based on prior literature on demographic and individual difference predictors (e.g., siblings of adults with autism with fewer problem behaviors would have increased health-related quality of life [HRQOL], decreased caregiver burden, and increased reported benefits) and on stress and coping factors related to the burden of providing care for an individual with autism (e.g., greater use of avoidant coping strategies would be related to lower HRQOL, increased caregiver burden, and decreased reports of benefits). Exploratory hypotheses also were examined (e.g., being married would be associated with increased HRQOL, decreased burden, and increased reported benefits). The within-subject results indicated support for eight of the ten primary hypotheses and five of the six exploratory hypotheses when examined within at least one of the study groups: Autism, DS, or Disability. Overall, sibling caregivers, regardless of their sibling’s disability, reported more favorable psychosocial outcomes when demands were lower (e.g., less severe levels of problem behaviors, fewer autism symptoms exhibited by their disabled sibling, decreased additional pile-up stress), when resources were available to cope with stress (e.g., social support, respite care), and when healthy responses to stress were reported (e.g., use of emotion focused vs. avoidant coping strategies, use of challenge vs. threat appraisal types). Of note, reported benefits, which have rarely been examined in the autism literature, were strongly related to the quality of a sibling relationship across all study groups, and with the helpfulness of received services and perceived social support within the Autism group. The between subject hypotheses also were largely supported. As expected, compared to siblings of those with Down syndrome, siblings of those with autism demonstrated greater levels of caregiver burden and lower mental HRQOL. Moreover, there was a rank ordering in levels of caregiver burden across disability groups; siblings of adults with DS reported the lowest burden, siblings of adults with DS with symptoms of autism reported significantly higher levels of burden, and siblings of those with autism reported the most burden. The results imply that autism, either alone or co-morbid with another diagnosis, presents an increased risk of stress and caregiver burden, not only in parent caregivers, but also in sibling caregivers. Interestingly, there was also evidence for higher levels of stress related growth within the Autism group compared to the DS group. Future research will be needed to generalize the results of this study to broader samples of adult siblings while taking a life course perspective to assess changes in non-disabled siblings’ outcomes over time.Item The relationship between implicit person theory and transformational leadership(2013-12-10) Kale, Aron Justin; Williams, Jane R.; Boyd, Elizabeth; Ashburn-Nardo, Leslie; Grahame, Nicholas J.Transformational leadership has been one of the most heavily researched theories of leadership of the past 25 years, largely because this style has been associated with a wide range of positive individual- and organizational-level outcomes. Despite the need for transformational leaders, the antecedents of transformational leadership behavior remain ambiguous. Numerous potential antecedents of transformational leadership have been identified in the past, but this research has focused on popularly addressed or commonly measured variables rather than characteristics with a strong theoretical link to transformational leadership. The current study expands on past research by examining a theoretically driven predictor of transformational leadership behavior. Specifically, the current study will examine whether a leader’s implicit person theory (IPT) will be a predictor of leadership behaviors. This theory was chosen as a potential antecedent because it centers on the concept of malleability or change, and as such shares a strong intuitive connection with transformational leadership (which itself places a heavy emphasis on change and growth). Results did not support our hypotheses, however, as regression analysis revealed that IPT failed to account for significant variation in leadership behavior after accounting for some of the most commonly examined predictors in the literature, (the Big Five personality traits). Limitations of the current study and opportunities for future research are discussed.