Flexible Modelling of Discrete Failure Time Including Time-Varying Smooth Effects

Discrete survival models have been extended in several ways. More flexible models are obtained by including time-varying coefficients and covariates which determine the hazard rate in an additive but not further specified form. In this paper a general model is considered which comprises both types of covariate effects. An additional extension is the incorporation of smooth interaction between time and covariates. Thus in the linear predictor smooth effects of covariates which may vary across time are allowed. It is shown how simple duration models produce artefacts which may be avoided by flexible models. For the general model which includes parametric terms, time-varying coefficients in parametric terms and time-varying smooth effects estimation procedures are derived which are based on the regularized expansion of smooth effects in basis functions

Defining and Estimating Intervention Effects for Groups that will Develop an Auxiliary Outcome

It has recently become popular to define treatment effects for subsets of the target population characterized by variables not observable at the time a treatment decision is made. Characterizing and estimating such treatment effects is tricky; the most popular but naive approach inappropriately adjusts for variables affected by treatment and so is biased. We consider several appropriate ways to formalize the effects: principal stratification, stratification on a single potential auxiliary variable, stratification on an observed auxiliary variable and stratification on expected levels of auxiliary variables. We then outline identifying assumptions for each type of estimand. We evaluate the utility of these estimands and estimation procedures for decision making and understanding causal processes, contrasting them with the concepts of direct and indirect effects. We motivate our development with examples from nephrology and cancer screening, and use simulated data and real data on cancer screening to illustrate the estimation methods.Comment: Published at http://dx.doi.org/10.1214/088342306000000655 in the Statistical Science (http://www.imstat.org/sts/) by the Institute of Mathematical Statistics (http://www.imstat.org

VULNERABILITY ASSESSMENT OF DWELLING BUILDINGS

Risk is defined as the potential economic, social and environmental consequences of hazardous events that may occur in a specified area unit and period. The evaluation of physical vulnerability and risk of buildings is the main purpose of this chapter. Nevertheless, it is shown the necessity of considering not only the expected physical damage but also the social fragility and the lack of resilience of the exposed community, that is, a holistic evaluation of risk aiming at guiding decision making.  Both the vulnerability index and capacity spectrum methods for the evaluation of the physical risk are discussed herein. Both provide good results for the considered case study the urban area of Barcelona, Spain. Both methods show how a city, located in a low to moderate hazard region, which has paid no attention to the seismic performance of their buildings, has buildings with a high seismic vulnerability and a considerable seismic risk

Convergent Set-Based Design in Integrated Analysis of Alternatives: Designing Engineered Resilient Systems

This thesis presents a comprehensive package for understanding and expanding set-based design quantification through the definition and demonstration of Convergent set-based design (SBD). Convergent SBD is a technique developed for the Engineered Resilient Systems program sponsored by the Department of Defense. Convergent SBD contributes a repeatable methodology with the goal of mathematically eliminating inefficient sets. The study of Convergent SBD led to the development of dominance identification criteria equations using comparison of statistical means. The demonstration of Convergent SBD also illustrates the effect of mission resilience in the tradespace and the impact mission resilience has on preference. Finally, Convergent SBD contributes to mathematical identification of the previously heuristic based set drivers and set modifiers and discusses additional decision analyst uses for this information. Presented as a complete thesis, Convergent SBD provides a foundational mathematical technique for eliminating sets and a method for converging to an efficient, affordable solution or group of solutions

Seismic vulnerability assessment of existing masonry buildings: case study of the old city centre of Faro, Portugal

The seismic vulnerability and risk assessment of old city centre areas is truly essential in urban rehabilitation programs and should not be focused exclusively over recognized historical and patrimonial valuable buildings but also in relation to current old masonry buildings that are highly valued in urban context. In addition, due to their geographical, demographic or historical features some old city centres are particularly interesting and critical, in respect to seismic risk mitigation. An excellent example of this reality is the old city of Faro, Capital of the Algarve, Portugal, which is one of the most popular summer touristic destination in Europe in a prone seismic region. This fact explains the high seasonal flux of population, which together with the moderate to high seismic hazard of the Algarve region and a vulnerable building stock increases both the seismic and tsunami risk in this area. From the exposed, this paper approaches the seismic vulnerability assessment of old building stock through the application of a simplified vulnerability method to the old city centre of Faro. Such method is based on a vulnerability index, which can be used to evaluate physical damage and to create human and economic loss scenarios in a broad sense (Vicente et al., 2011). 191 buildings were evaluated in accordance with the referred methodology and the results obtained were subsequently integrated into a Geographical Information System (GIS) tool, which allows the spatial analysis of results (Ferreira et al., 2013).This tool constitutes a very valuable instrument for city councils and regional authorities, whom can decide in a faster and more accurate way the best risk mitigation strategies to follow at the urban scale.info:eu-repo/semantics/publishedVersio

Seismic risk assessment of residential buildings by the Heuristic vulnerability model: influence of fragility curve models and inventory scale

Typological-observational methods still constitute one of the most commonly applied tools for evaluation of the seismic risk and vulnerability of the existing building stock. Their efficiency is mainly related to the effectiveness of the procedure for deriving fragility curves, and the reliability and completeness of the database that describes the building stock. This paper presents a comparison between the vulnerability and damage distribution assessment provided by fragility curves used in the Macroseismic and Heuristic methods, and a comparison of exposure evaluation methodologies according to two different approaches, namely a compartment- and a building-scale survey. An application to the case study of the residential building stock in the historic center of Alcamo, a town of 45,000 inhabitants in Western Sicily (Italy), shows the major reduction in fragility provided by recalibration of the masonry buildings’ ductility values that characterize the Heuristic method. Moreover, the efficiency of the compartment scale survey approach, based on the CARTIS typological-structural characterization method of ordinary buildings in urban areas, is underlined