16 resultados para Panel Data Model
em BORIS: Bern Open Repository and Information System - Berna - Suiça
Resumo:
The past 1500 years provide a valuable opportunity to study the response of the climate system to external forcings. However, the integration of paleoclimate proxies with climate modeling is critical to improving the understanding of climate dynamics. In this paper, a climate system model and proxy records are therefore used to study the role of natural and anthropogenic forcings in driving the global climate. The inverse and forward approaches to paleoclimate data–model comparison are applied, and sources of uncertainty are identified and discussed. In the first of two case studies, the climate model simulations are compared with multiproxy temperature reconstructions. Robust solar and volcanic signals are detected in Southern Hemisphere temperatures, with a possible volcanic signal detected in the Northern Hemisphere. The anthropogenic signal dominates during the industrial period. It is also found that seasonal and geographical biases may cause multiproxy reconstructions to overestimate the magnitude of the long-term preindustrial cooling trend. In the second case study, the model simulations are compared with a coral δ18O record from the central Pacific Ocean. It is found that greenhouse gases, solar irradiance, and volcanic eruptions all influence the mean state of the central Pacific, but there is no evidence that natural or anthropogenic forcings have any systematic impact on El Niño–Southern Oscillation. The proxy climate relationship is found to change over time, challenging the assumption of stationarity that underlies the interpretation of paleoclimate proxies. These case studies demonstrate the value of paleoclimate data–model comparison but also highlight the limitations of current techniques and demonstrate the need to develop alternative approaches.
Resumo:
A main assumption of social production function theory is that status is a major determinant of subjective well-being (SWB). From the perspective of the dissociative hypothesis, however, upward social mobility may be linked to identity problems, distress, and reduced levels of SWB because upwardly mobile people lose their ties to their class of origin. In this paper, we examine whether or not one of these arguments holds. We employ the United Kingdom and Switzerland as case studies because both are linked to distinct notions regarding social inequality and upward mobility. Longitudinal multilevel analyses based on panel data (UK: BHPS, Switzerland: SHP) allow us to reconstruct individual trajectories of life satisfaction (as a cognitive component of SWB) along with events of intragenerational and intergenerational upward mobility—taking into account previous levels of life satisfaction, dynamic class membership, and well-studied determinants of SWB. Our results show some evidence for effects of social class and social mobility on well-being in the UK sample, while there are no such effects in the Swiss sample. The UK findings support the idea of dissociative effects in terms of a negative effect of intergenerational upward mobility on SWB.
Resumo:
Results from the Zurich study have shown lasting associations between sport practice and mental health. The effects are pronounced in people with pre-exising mental health problems. This analysis aims to replicate these results with the large Swiss Household Panel data set and to provide more differentiated results. The analysis covered the interviews 1999-2003 and included 3891 stayers, i.e., participants who were interviewed in all years. The outcome variables are depression / blues / anxiety, weakness / weariness, sleeping problems, energy / optimism. Confounding variables include sex, age, education level, citizenship. The analyses were carried out with mixed models (depression, optimism) and GEE models (weakness, sleep). About 60% of the SHP participants practise weekly or daily an individual or a team sport. A similar proportion enjoys a frequent physical activity (for half an hour minimum) which makes oneself slightly breathless. There are slight age-specific differences but also noteworthy regional differences. Practice of sport is clearly interrelated with self-reported depressive symptoms, optimism and weakness. This applies even though some relevant confounders – sex, educational level and citizenship – were introduced into the model. However, no relevant interaction effects with time could be shown. Moreover, direct interrelations commonly led to better fits than models with lagged variables, thus indicating that delayed effects of sport practice on the self-reported psychological complaints are less important. Model variants resulted for specific subgroups, for example, participants with a high vs. low initial activity level. Lack of sport practice is an interesting marker for serious psychological symptoms and mental disorders. The background of this association may differ in different subgroups, and should stimulate further investigations in this area.
Resumo:
The paper considers panel data methods for estimating ordered logit models with individual-specific correlated unobserved heterogeneity. We show that a popular approach is inconsistent, whereas some consistent and efficient estimators are available, including minimum distance and generalized method-of-moment estimators. A Monte Carlo study reveals the good properties of an alternative estimator that has not been considered in econometric applications before, is simple to implement and almost as efficient. An illustrative application based on data from the German Socio-Economic Panel confirms the large negative effect of unemployment on life satisfaction that has been found in the previous literature.
Resumo:
Im vorliegenden Beitrag wird die Zuverlässigkeit retrospektiver Angaben der Befragten zu beruflichen Tätigkeiten in ihrem Berufsverlauf untersucht. Insbesondere ist ausgehend von einem Befund von De Graaf und Wegener (1989) zu klären, ob generell Beschäftigte des öffentlichen Dienstes ihren Berufsverlauf unzuverlässiger erinnern als Staatsbeschäftigte. Es wird davon ausgegangen, dass gerade Beamte aufgrund der institutionellen Besonderheiten ihrer Beschäftigung größere Schwierigkeiten haben, ihren Berufsverlauf konsistent zu rekonstruieren als andere Befragte. Empirische Analysen von Panel-Daten erhärten diese Vermutung, was die Anzahl der beruflichen Tätigkeiten anbelangt. Jedoch machen Beamte zu anderen Attributen ihres Berufsverlaufs ebenso zuverlässige Angaben wie andere Befragte auch. Diese beamtenspezifischen Erinnerungsprobleme sind bei zukünftigen Erhebungen mittels ereignisorientierter Befragungsinstrumente zu berücksichtigen.
Resumo:
This paper is concerned with the analysis of zero-inflated count data when time of exposure varies. It proposes a modified zero-inflated count data model where the probability of an extra zero is derived from an underlying duration model with Weibull hazard rate. The new model is compared to the standard Poisson model with logit zero inflation in an application to the effect of treatment with thiotepa on the number of new bladder tumors.
Resumo:
Tropical explosive volcanism is one of the most important natural factors that significantly impact the climate system and the carbon cycle on annual to multi-decadal time scales. The three largest explosive eruptions in the last 50�years�Agung, El Chichón, and Pinatubo�occurred in spring/summer in conjunction with El Niño events and left distinct negative signals in the observational temperature and CO2 records. However, confounding factors such as seasonal variability and El Niño-Southern Oscillation (ENSO) may obscure the forcing-response relationship. We determine for the first time the extent to which initial conditions, i.e., season and phase of the ENSO, and internal variability influence the coupled climate and carbon cycle response to volcanic forcing and how this affects estimates of the terrestrial and oceanic carbon sinks. Ensemble simulations with the Earth System Model (Climate System Model 1.4-carbon) predict that the atmospheric CO2 response is �60 larger when a volcanic eruption occurs during El Niño and in winter than during La Niña conditions. Our simulations suggest that the Pinatubo eruption contributed 11�±�6 to the 25�Pg terrestrial carbon sink inferred over the decade 1990�1999 and �2�±�1 to the 22�Pg oceanic carbon sink. In contrast to recent claims, trends in the airborne fraction of anthropogenic carbon cannot be detected when accounting for the decadal-scale influence of explosive volcanism and related uncertainties. Our results highlight the importance of considering the role of natural variability in the carbon cycle for interpretation of observations and for data-model intercomparison.
Resumo:
Within Western societies women or girls meanwhile outperform men or boys with regard to attainments in primary and secondary education. For example concerning upper secondary degrees the share of females attaining the Matura approaches two thirds in Switzerland, while the share of females attaining the Baccalaureate exceeds fifty per cent in France. However, if transitions to higher education are regarded, the share of entitled females entering such institutions is significantly lower than among men in Switzerland. An opposite pattern is observed in France where females outperform men at this educational stage, too. With regard to migrant background, it has been shown by previous research focussing on secondary effects of ethnic origin that such youths enter the more demanding educational tracks (e.g. higher education) more often than their non-migrant peers if controlled for eligibility, their lower socioeconomic status and performances. However, so far only a few studies refer to the question of a possible gender gap regarding secondary effects of ethnic origin (e.g. Fleischmann et al., mimeo). Thus, with regard to a possible interaction of a migrant background and - for example - a female gender, it is important to note that in both countries many migrant groups have their origins in countries and regions where male advantage remains very strong. This is in particular the case for migrant groups from non-Western countries, e.g. Turkey, Algeria, Marocco or Tunisie, where gender gaps in the literacy rates of up to 18 per cent are still observed. In order to investigate the question of a possible disadvantages of women with a migrant background stemming from such countries when compared to non-migrant females two panel studies - the Tree data in Switzerland and the Panel d’élèves 1995 in France -, are analysed.
Resumo:
Synaptic plasticity rules change during development: while hippocampal synapses can be potentiated by a single action potential pairing protocol in young neurons, mature neurons require burst firing to induce synaptic potentiation. An essential component for spike timing-dependent plasticity is the backpropagating action potential (BAP). BAP along the dendrites can be modulated by morphology and ion channel composition, both of which change during late postnatal development. However it is unclear whether these dendritic changes can explain the developmental changes in synaptic plasticity induction rules. Here, we show that tonic GABAergic inhibition regulates dendritic action potential backpropagation in adolescent but not pre-adolescent CA1 pyramidal neurons. These developmental changes in tonic inhibition also altered the induction threshold for spike timing-dependent plasticity in adolescent neurons. This GABAergic regulatory effect upon backpropagation is restricted to distal regions of apical dendrites (>200 μm) and mediated by α5-containing GABA(A) receptors. Direct dendritic recordings demonstrate α5-mediated tonic GABA(A) currents in adolescent neurons which can modulate backpropagating action potentials. These developmental modulations in dendritic excitability could not be explained by concurrent changes in dendritic morphology. To explain our data, model simulations propose a distally-increasing or localized distal expression of dendritic α5 tonic inhibition in mature neurons. Overall, our results demonstrate that dendritic integration and plasticity in more mature dendrites are significantly altered by tonic α5 inhibition in a dendritic region-specific and developmentally-regulated manner.
Resumo:
Sequence analysis and optimal matching are useful heuristic tools for the descriptive analysis of heterogeneous individual pathways such as educational careers, job sequences or patterns of family formation. However, to date it remains unclear how to handle the inevitable problems caused by missing values with regard to such analysis. Multiple Imputation (MI) offers a possible solution for this problem but it has not been tested in the context of sequence analysis. Against this background, we contribute to the literature by assessing the potential of MI in the context of sequence analyses using an empirical example. Methodologically, we draw upon the work of Brendan Halpin and extend it to additional types of missing value patterns. Our empirical case is a sequence analysis of panel data with substantial attrition that examines the typical patterns and the persistence of sex segregation in school-to-work transitions in Switzerland. The preliminary results indicate that MI is a valuable methodology for handling missing values due to panel mortality in the context of sequence analysis. MI is especially useful in facilitating a sound interpretation of the resulting sequence types.
Resumo:
Various avours of a new research field on (socio-)physical or personal analytics have emerged, with the goal of deriving semantically-rich insights from people's low-level physical sensing combined with their (online) social interactions. In this paper, we argue for more comprehensive data sources, including environmental (e.g. weather, infrastructure) and application-specific data, to better capture the interactions between users and their context, in addition to those among users. To illustrate our proposed concept of synergistic user <-> context analytics, we first provide some example use cases. Then, we present our ongoing work towards a synergistic analytics platform: a testbed, based on mobile crowdsensing and the Internet of Things (IoT), a data model for representing the different sources of data and their connections, and a prediction engine for analyzing the data and producing insights.
Resumo:
How do institutional settings and their embedded policy principles affect gender-typed enrolment in educational programmes? Based on gender-sensitive theories on career choice, we hypothesised that gender segregation in education is higher with a wider range of offers of vocational programmes. By analysing youth survey and panel data, we tested this assumption for Germany, Norway and Canada, three countries whose educational systems represent a different mix of academic, vocational and universalistic education principles. We found that vocational programmes are considerably more gender-segregated than are academic (e.g. university) programmes. Men, more so than women, can avoid gender-typed programmes by passing on to a university education. This in turn means that as long as their secondary school achievement does not allow for a higher education career, they have a higher likelihood of being allocated to male-typed programmes in the vocational education and training (VET) system. In addition, social background and the age at which students have to choose educational offers impact on the transition to gendered educational programmes. Overall, gender segregation in education is highest in Germany and the lowest in Canada. We interpret the differences between these countries with respect to the constellations of educational principles and policies in the respective countries.
Resumo:
This paper reviews the methods, benefits and challenges associated with the adoption and translation of computational fluid dynamics (CFD) modelling within cardiovascular medicine. CFD, a specialist area of mathematics and a branch of fluid mechanics, is used routinely in a diverse range of safety-critical engineering systems, which increasingly is being applied to the cardiovascular system. By facilitating rapid, economical, low-risk prototyping, CFD modelling has already revolutionised research and development of devices such as stents, valve prostheses, and ventricular assist devices. Combined with cardiovascular imaging, CFD simulation enables detailed characterisation of complex physiological pressure and flow fields and the computation of metrics which cannot be directly measured, for example, wall shear stress. CFD models are now being translated into clinical tools for physicians to use across the spectrum of coronary, valvular, congenital, myocardial and peripheral vascular diseases. CFD modelling is apposite for minimally-invasive patient assessment. Patient-specific (incorporating data unique to the individual) and multi-scale (combining models of different length- and time-scales) modelling enables individualised risk prediction and virtual treatment planning. This represents a significant departure from traditional dependence upon registry-based, population-averaged data. Model integration is progressively moving towards 'digital patient' or 'virtual physiological human' representations. When combined with population-scale numerical models, these models have the potential to reduce the cost, time and risk associated with clinical trials. The adoption of CFD modelling signals a new era in cardiovascular medicine. While potentially highly beneficial, a number of academic and commercial groups are addressing the associated methodological, regulatory, education- and service-related challenges.
Resumo:
Dass es geschlechtstypische Berufe gibt, und dass die Berufsaspirationen und die Wahl der Berufsausbildung nach der Pflichtschulzeit zwischen den Geschlechtern deutlich differieren, ist eine vielfach empirisch belegte Tatsache. Diese geschlechtstypische Segregation bei der Berufswahl und der zum ausgewählten Beruf führenden schulischen und beruflichen Ausbildung wird bei der Erklärung oftmals (pauschal) auf die geschlechtsspezifische Sozialisation und darin vermittelte Geschlechterstereotype zurückgeführt. Im vorliegenden Beitrag werden aus strukturell-individualistischer Sicht Mechanismen der geschlechtstypischen Berufsaspiration und Berufsbildungsentscheidung beschrieben, die theoriegeleitet empirisch aufgedeckt werden sollen. Für die Analysen werden Daten der drei Wellen des DAB-Panels verwendet, die für die Deutschschweiz Informationen von 203 Schulklassen mit rund 3.300 Schülerinnen und Schüler zur Verfügung stellen. Mittels dieser Paneldaten wird für Jugendliche der Deutschschweiz gezeigt, dass der sozioökonomische Status des Elternhauses, das damit einhergehende Motiv des intergenerationalen Statuserhalts sowie der Lebenslaufplanungen wichtige Beiträge zur Erklärung der Segregation der Berufswahl nach Geschlecht liefern. Diese mit dem Sozialstatus des Elternhauses verbundenen Mechanismen sind weitaus einflussreicher als die geschlechtsspezifische Sozialisation.