14 resultados para multilevel models

em BORIS: Bern Open Repository and Information System - Berna - Suiça


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OBJECTIVES: To estimate changes in coronary risk factors and their implications for coronary heart disease (CHD) rates in men starting highly active antiretroviral therapy (HAART). METHODS: Men participating in the Swiss HIV Cohort Study with measurements of coronary risk factors both before and up to 3 years after starting HAART were identified. Fractional polynomial regression was used to graph associations between risk factors and time on HAART. Mean risk factor changes associated with starting HAART were estimated using multilevel models. A prognostic model was used to predict corresponding CHD rate ratios. RESULTS: Of 556 eligible men, 259 (47%) started a nonnucleoside reverse transcriptase inhibitor (NNRTI) and 297 a protease inhibitor (PI) based regimen. Levels of most risk factors increased sharply during the first 3 months on HAART, then more slowly. Increases were greater with PI- than NNRTI-based HAART for total cholesterol (1.18 vs. 0.98 mmol L(-1)), systolic blood pressure (3.6 vs. 0 mmHg) and BMI (1.04 vs. 0.55 kg m(2)) but not HDL cholesterol (0.24 vs. 0.32 mmol L(-1)) or glucose (1.02 vs. 1.03 mmol L(-1)). Predicted CHD rate ratios were 1.40 (95% CI 1.13-1.75) and 1.17 (0.95-1.47) for PI- and NNRTI-based HAART respectively. CONCLUSIONS: Coronary heart disease rates will increase in a majority of patients starting HAART: however the increases corresponding to typical changes in risk factors are relatively modest and could be offset by lifestyle changes.

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In 186 patients with early colon cancer, we investigated the assumption that the meaning of 'quality of life' (QL) remains constant over time. Within a phase-III trial (SAKK 40/93), patients estimated both their overall QL and a range of disease- and treatment-related domains at five timepoints, comprising three concurrent and 2 retrospective estimates: their pre-surgery QL both before surgery and retrospectively thereafter, and their pre-adjuvant QL both at the beginning of adjuvant treatment and retrospectively about 2 months later, and their current QL 2 weeks thereafter. Multilevel models were developed to determine whether the selected domains made stable contributions to overall QL at the concurrent estimates. The weights of the domains changed over time. They did not differ significantly according to whether patients were considering their concurrent state or reflecting on this state at a later timepoint. In the process of adaptation, patients with early colon cancer substantially change the relative importance of QL domains to overall QL. This finding argues for QL as a changing construct and against the assumption that domain-specific weights are stable across distinct clinical phases.

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Little is known about political polarization in German public opinion. This article offers an issue-based perspective and explores trends of opinion polarization in Germany. Public opinion polarization is conceptualized and measured as alignment of attitudes. Data from the German General Social Survey (1980 to 2010) comprise attitudes towards manifold issues, which are classified into several dimensions. This study estimates multilevel models that reveal general and issue- as well as dimension-specific levels and trends in attitude alignment for both the whole German population and sub-groups. It finds that public opinion polarization has decreased over the last three decades in Germany. In particular, highly educated and more politically interested people have become less polarized over time. However, polarization seems to have increased in attitudes regarding gender issues. These findings provide interesting contrasts to existing research on the American public.

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This paper analyzes the development of environmental concern by using the three waves of the environmental modules of the International Social Survey Programme. First, we discuss the measurement of environmental concern and construct a ranking of countries according to the new 2010 results. Second, we analyze the determinants of environmental concern by employing multilevel models that take individual as well as context effects into account. Third, we explore the longitudinal aspect of the data at the macro level in order to uncover the causal relation between countries’ wealth and environmental concern. The results show that environmental concern is closely correlated with the wealth of the nations. However, environmental concern decreased in almost all nations slightly during the last two decades. The decline was lower in countries with improving economic conditions suggesting that economic growth helps to maintain higher levels of environmental concern.

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This paper analyzes the development of environmental concern by using the three waves of the environmental modules of the International Social Survey Programme (ISSP). First, we discuss the measurement of environmental concern and construct a ranking of countries according to the new 2010 ISSP results. Second, we analyze the determinants of environmental concern by employing multilevel models that take individual as well as context effects into account. Third, we explore the impact of attitudes on environmental behavior and support of environmental policies. The results show that environmental concern is closely correlated with the wealth of nations. However, environmental concern decreased in OECD as well as non-OECD nations slightly during the last two decades. The decline was lower in countries with improving economic conditions suggesting that economic growth helps to maintain higher levels of environmental concern. Furthermore, attitudes have a stronger impact on support of environmental policies as compared to everyday environmental behavior.

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The article offers a systematic analysis of the comparative trajectory of international democratic change. In particular, it focuses on the resulting convergence or divergence of political systems, borrowing from the literatures on institutional change and policy convergence. To this end, political-institutional data in line with Arend Lijphart’s (1999, 2012) empirical theory of democracy for 24 developed democracies between 1945 and 2010 are analyzed. Heteroscedastic multilevel models allow for directly modeling the development of the variance of types of democracy over time, revealing information about convergence, and adding substantial explanations. The findings indicate that there has been a trend away from extreme types of democracy in single cases, but no unconditional trend of convergence can be observed. However, there are conditional processes of convergence. In particular, economic globalization and the domestic veto structure interactively influence democratic convergence.

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This article combines the research strands of moral politics and political behavior by focusing on the effect of individual and contextual religiosity on individual vote decisions in popular initiatives and public referenda concerning morally charged issues. We rely on a total of 13 surveys with 1,000 respondents each conducted after every referendum on moral policies in Switzerland between 1992 and 2012. Results based on cross-classified multilevel models show that religious behaving instead of nominal religious belonging plays a crucial role in decision making on moral issues. This supports the idea that the traditional confessional cleavage is replaced by a new religious cleavage that divides the religious from the secular. This newer cleavage is characterized by party alignments that extend from electoral to direct democratic voting behavior. Overall, our study lends support to previous findings drawn from American research on moral politics, direct democracies, and the public role of religion.

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Caregiving for individuals with Alzheimer's disease is associated with chronic stress and elevated symptoms of depression. Placement of the care receiver (CR) into a long-term care setting may be associated with improved caregiver well-being; however, the psychological mechanisms underlying this relationship are unclear. This study evaluated whether decreases in activity restriction and increases in personal mastery mediated placement-related reductions in caregiver depressive symptoms. In a 5-year longitudinal study of 126 spousal Alzheimer's disease caregivers, we used multilevel models to evaluate placement-related changes in depressive symptoms (short form of the Center for Epidemiologic Studies Depression scale), activity restriction (Activity Restriction Scale), and personal mastery (Pearlin Mastery Scale) in 44 caregivers who placed their spouses into long-term care relative to caregivers who never placed their CRs. The Monte Carlo method for assessing mediation was used to evaluate the significance of the indirect effect of activity restriction and personal mastery on postplacement changes in depressive symptoms. Placement of the CR was associated with significant reductions in depressive symptoms and activity restriction and was also associated with increased personal mastery. Lower activity restriction and higher personal mastery were associated with reduced depressive symptoms. Furthermore, both variables significantly mediated the effect of placement on depressive symptoms. Placement-related reductions in activity restriction and increases in personal mastery are important psychological factors that help explain postplacement reductions in depressive symptoms. The implications for clinical care provided to caregivers are discussed.

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This article addresses factors that infl uence member commitment in sport clubs. Based on the theory of social action and the economic behaviour theory, it focuses not only on individual characteristics of club members but also on the corresponding structural conditions of sport clubs. Accordingly, a multilevel framework is developed for explaining member commitment in sport clubs. Different multilevel models were estimated in order to analyse the infl uences of both the individual and corresponding context Level in a sample of n = 1,699 members of 42 Swiss and German sport clubs. The multilevel analysis permitted an adequate handling of hierarchically structured data. Results of These multilevel analyses indicated that the commitment of members is not just an outcome of individual characteristics such as strong identifi cation with their club, positively perceived (collective) solidarity, satisfaction with their sport club, or voluntary engagement. It is also determined by club-specific structural conditions: commitment proves to be more probable in rural sport clubs and clubs that explicitly support sociability. Furthermore, cross-level effects in relation to member commitment were also found between the context variable sociability and the individual variable identification.

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Several theories assume that successful team coordination is partly based on knowledge that helps anticipating individual contributions necessary in a situational task. It has been argued that a more ecological perspective needs to be considered in contexts evolving dynamically and unpredictably. In football, defensive plays are usually coordinated according to strategic concepts spanning all members and large areas of the playfield. On the other hand, fewer people are involved in offensive plays as these are less projectable and strongly constrained by ecological characteristics. The aim of this study is to test the effects of ecological constraints and player knowledge on decision making in offensive game scenarios. It is hypothesized that both knowledge about team members and situational constraints will influence decisional processes. Effects of situational constraints are expected to be of higher magnitude. Two teams playing in the fourth league of the Swiss Football Federation participate in the study. Forty customized game scenarios were developed based on the coaches’ information about player positions and game strategies. Each player was shown in ball possession four times. Participants were asked to take the perspective of the player on the ball and to choose a passing destination and a recipient. Participants then rated domain specific strengths (e.g., technical skills, game intelligence) of each of their teammates. Multilevel models for categorical dependent variables (team members) will be specified. Player knowledge (rated skills) and ecological constraints (operationalized as each players’ proximity and availability for ball reception) are included as predictor variables. Data are currently being collected. Results will yield effects of parameters that are stable across situations as well as of variable parameters that are bound to situational context. These will enable insight into the degree to which ecological constraints and more enduring team knowledge are involved in decisional processes aimed at coordinating interpersonal action.