17 resultados para competing risks model

em Consorci de Serveis Universitaris de Catalunya (CSUC), Spain


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Applying the competing--risks model to multi--cause mortality,this paper provides a theoretical and empirical investigation of the positive complementarities that occur between disease--specific policy interventions. We argue that since an individual cannot die twice, competing risks imply that individuals will not waste resources on causes that are not the most immediate, but will make health investments so as to equalize cause--specific mortality. However, equal mortality risk from a variety of diseases does not imply that disease--specific public health interventions are a waste. Rather, a cause--specific intervention produces spillovers to other disease risks, so that the overall reduction in mortality will generally be larger than the direct effect measured on the targeted disease. The assumption that mortality from non--targeted diseases remains the same after a cause--specific intervention under--estimates the true effect of such programs, since the background mortality is also altered as a result of intervention. Analyzing data from one of the most important public health programs ever introduced, the Expanded Program on Immunization (EPI) of the United Nations, we find evidence for the existence of such complementarities, involving causes that are not biomedically, but behaviorally, linked.

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Background: Breast cancer mortality has experienced important changes over the last century. Breast cancer occurs in the presence of other competing risks which can influence breast cancer incidence and mortality trends. The aim of the present work is: 1) to assess the impact of breast cancer deaths among mortality from all causes in Catalonia (Spain), by age and birth cohort and 2) to estimate the risk of death from other causes than breast cancer, one of the inputs needed to model breast cancer mortality reduction due to screening or therapeutic interventions. Methods: The multi-decrement life table methodology was used. First, all-cause mortality probabilities were obtained by age and cohort. Then mortality probability for breast cancer was subtracted from the all-cause mortality probabilities to obtain cohort life tables for causes other than breast cancer. These life tables, on one hand, provide an estimate of the risk of dying from competing risks, and on the other hand, permit to assess the impact of breast cancer deaths on all-cause mortality using the ratio of the probability of death for causes other than breast cancer by the all-cause probability of death. Results: There was an increasing impact of breast cancer on mortality in the first part of the 20th century, with a peak for cohorts born in 1945–54 in the 40–49 age groups (for which approximately 24% of mortality was due to breast cancer). Even though for cohorts born after 1955 there was only information for women under 50, it is also important to note that the impact of breast cancer on all-cause mortality decreased for those cohorts. Conclusion: We have quantified the effect of removing breast cancer mortality in different age groups and birth cohorts. Our results are consistent with US findings. We also have obtained an estimate of the risk of dying from competing-causes mortality, which will be used in the assessment of the effect of mammography screening on breast cancer mortality in Catalonia.

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This paper studies the duration pattern of xed-term contracts and the determinantsof their conversion into permanent ones in Spain, where the share of xed-termemployment is the highest in Europe. We estimate a duration model for temporaryemployment, with competing risks of terminating into permanent employment versusalternative states, and exible duration dependence. We nd that conversion rates aregenerally below 10%. Our estimated conversion rates roughly increase with tenure,with a pronounced spike at the legal limit, when there is no legal way to retain theworker on a temporary contract. We argue that estimated di¤erences in conversionrates across categories of workers can stem from di¤erences in worker outside optionsand thus the power to credibly threat to quit temporary jobs.

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The public perception of the EU in Spain varies greatly. The most positive aspects of Spanish membership are associated with the consolidation of democracy, economic growth, the introduction of the euro, the growth in employment and structural and cohesion funds, the increase in the female participation rate, and the equal opportunities policies. The analysts are in favour of common objectives in the employment policy and multi-level government. The less positive aspects of the EU are the risks of losing social protection and loss of employment in some sectors due to mergers of multinationals and delocalization of companies towards Eastern Europe. The continuous demands for reform of the welfare state, the toughening of the conditions of access to social benefit and the reform of the labour market are also seen as problematic issues. Risks of competitive cuts and social dumping.

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Recently there has been a renewed research interest in the properties of non survey updates of input-output tables and social accounting matrices (SAM). Along with the venerable and well known scaling RAS method, several alternative new procedures related to entropy minimization and other metrics have been suggested, tested and used in the literature. Whether these procedures will eventually substitute or merely complement the RAS approach is still an open question without a definite answer. The performance of many of the updating procedures has been tested using some kind of proximity or closeness measure to a reference input-output table or SAM. The first goal of this paper, in contrast, is the proposal of checking the operational performance of updating mechanisms by way of comparing the simulation results that ensue from adopting alternative databases for calibration of a reference applied general equilibrium model. The second goal is to introduce a new updatin! g procedure based on information retrieval principles. This new procedure is then compared as far as performance is concerned to two well-known updating approaches: RAS and cross-entropy. The rationale for the suggested cross validation is that the driving force for having more up to date databases is to be able to conduct more current, and hopefully more credible, policy analyses.

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To measure the contribution of individual transactions inside the total risk of a credit portfolio is a major issue in financial institutions. VaR Contributions (VaRC) and Expected Shortfall Contributions (ESC) have become two popular ways of quantifying the risks. However, the usual Monte Carlo (MC) approach is known to be a very time consuming method for computing these risk contributions. In this paper we consider the Wavelet Approximation (WA) method for Value at Risk (VaR) computation presented in [Mas10] in order to calculate the Expected Shortfall (ES) and the risk contributions under the Vasicek one-factor model framework. We decompose the VaR and the ES as a sum of sensitivities representing the marginal impact on the total portfolio risk. Moreover, we present technical improvements in the Wavelet Approximation (WA) that considerably reduce the computational effort in the approximation while, at the same time, the accuracy increases.

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We present a standard model of financial innovation, in which intermediaries engineer securities with cash flows that investors seek, but modify two assumptions. First, investors (and possibly intermediaries) neglect certain unlikely risks. Second, investors demand securities with safe cash flows. Financial intermediaries cater to these preferences and beliefs by engineering securities perceived to be safe but exposed to neglected risks. Because the risks are neglected, security issuance is excessive. As investors eventually recognize these risks, they fly back to safety of traditional securities and markets become fragile, even without leverage, precisely because the volume of new claims is excessive.

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We present a model of shadow banking in which financial intermediaries originate and trade loans, assemble these loans into diversified portfolios, and then finance these portfolios externally with riskless debt. In this model: i) outside investor wealth drives the demand for riskless debt and indirectly for securitization, ii) intermediary assets and leverage move together as in Adrian and Shin (2010), and iii) intermediaries increase their exposure to systematic risk as they reduce their idiosyncratic risk through diversification, as in Acharya, Schnabl, and Suarez (2010). Under rational expectations, the shadow banking system is stable and improves welfare. When investors and intermediaries neglect tail risks, however, the expansion of risky lending and the concentration of risks in the intermediaries create financial fragility and fluctuations in liquidity over time.

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We study a dynamic general equilibrium model where innovation takes theform of the introduction of new goods whose production requires skilled workers.Innovation is followed by a costly process of standardization, whereby these newgoods are adapted to be produced using unskilled labor. Our framework highlightsa number of novel results. First, standardization is both an engine of growth anda potential barrier to it. As a result, growth is an inverse U-shaped function ofthe standardization rate (and of competition). Second, we characterize the growthand welfare maximizing speed of standardization. We show how optimal protection of intellectual property rights affecting the cost of standardization vary withthe skill-endowment, the elasticity of substitution between goods and other parameters. Third, we show that, depending on how competition between innovatingand standardizing firms is modelled and on parameter values, a new type of multiplicity of equilibria may arise. Finally, we study the implications of our model forthe skill-premium and we illustrate novel reasons for linking North-South trade tointellectual property rights protection.

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We present a standard model of financial innovation, in which intermediaries engineer securities with cash flows that investors seek, but modify two assumptions. First, investors (and possibly intermediaries) neglect certain unlikely risks. Second, investors demand securities with safe cash flows. Financial intermediaries cater to these preferences and beliefs by engineering securities perceived to be safe but exposed to neglected risks. Because the risks are neglected, security issuance is excessive. As investors eventually recognize these risks, they fly back to safety of traditional securities and markets become fragile, even without leverage, precisely because the volume of new claims is excessive.

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Most optimistic views, based on Optimum Currency Areas (OCA) literature, have concluded that the probability of asymmetric shocks to occur at anational level will tend to diminish in the Economic and Monetary Union (EMU)as a result of the intensification of the integration process during the most recent years. Therefore, since Economic Geography Theories predict a higherspecialisation of regions, it is expected that asymmetric shocks will increase.Previous studies have examined to what extent asymmetric shocks have been relevant in the past using, mainly, static measures of asymmetries such as the correlation coefficients between series of shocks previously calculated from astructural VAR model (Bayoumi and Eichengreen, 1992).In this paper, we study the evolution of manufacturing specific asymmetries in Europe from a dynamic point of view (applying the modelproposed by Haldane and Hall, 1991) in order to obtain new evidence about potential risks of EMU.

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Most optimistic views, based on Optimum Currency Areas (OCA) literature, have concluded that the probability of asymmetric shocks to occur at anational level will tend to diminish in the Economic and Monetary Union (EMU)as a result of the intensification of the integration process during the most recent years. Therefore, since Economic Geography Theories predict a higherspecialisation of regions, it is expected that asymmetric shocks will increase.Previous studies have examined to what extent asymmetric shocks have been relevant in the past using, mainly, static measures of asymmetries such as the correlation coefficients between series of shocks previously calculated from astructural VAR model (Bayoumi and Eichengreen, 1992).In this paper, we study the evolution of manufacturing specific asymmetries in Europe from a dynamic point of view (applying the modelproposed by Haldane and Hall, 1991) in order to obtain new evidence about potential risks of EMU.

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We report Monte Carlo results for a nonequilibrium Ising-like model in two and three dimensions. Nearest-neighbor interactions J change sign randomly with time due to competing kinetics. There follows a fast and random, i.e., spin-configuration-independent diffusion of Js, of the kind that takes place in dilute metallic alloys when magnetic ions diffuse. The system exhibits steady states of the ferromagnetic (antiferromagnetic) type when the probability p that J>0 is large (small) enough. No counterpart to the freezing phenomena found in quenched spin glasses occurs. We compare our results with existing mean-field and exact ones, and obtain information about critical behavior.