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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Modelling dependent risks for insurer risk management: experimental studies with copulas

Wu, Mei Lan, Actuarial Studies, Australian School of Business, UNSW January 2007 (has links)
The increase in the use of copulas has introduced implementation issues for both practitioners and researchers. One of the issues is to obtain a copula function for a given set of data. The most common approaches for the estimation of the parameters of the copula functions have been the Maximum Likelihood Estimator (MLE) and the Inference Functions for Margins (IFM) methods. Archimedean copulas are one of the most important classes of copulas that are widely used in both finance and insurance for modelling dependent risks. However, simulating multivariate Archimedean copulas has always been a difficult task as the number of dimensions increases. The assessment of capital requirements has always been an important application of stochastic modelling. Capital requirements can vary significantly depending on the model adopted. Several professional bodies have recently discussed the concept of dependencies between insurance risks. They suggest that insurers should use a technique based on copulas to describe the dependence of risks within an insurance company in the context of solvency assessment. The first contribution of this thesis is to provide an insight into the efficiency of parameter estimation methods. This thesis uses numerical experiments to assess the performance of the two common approaches. The second contribution of this thesis is to present a new algorithm to simulate multivariate Exchangeable Archimedean copulas. This algorithm provides a practical solution for simulating one-parameter multivariate Archimedean copulas. Numerical experiments are used to apply this algorithm to determine the "additional" economic capital for an insurance company with multiple lines of business that wants to expand its business by adding another line of business and where the businesses are dependent. The third contribution of this thesis is to quantify the impact of the choice of copulas on the solvency measure of a general insurer within a Dynamic Financial Analysis modelling framework. The results of our experiments provide important guidance for the capital assessment for general insurers.
2

Modelling dependent risks for insurer risk management: experimental studies with copulas

Wu, Mei Lan, Actuarial Studies, Australian School of Business, UNSW January 2007 (has links)
The increase in the use of copulas has introduced implementation issues for both practitioners and researchers. One of the issues is to obtain a copula function for a given set of data. The most common approaches for the estimation of the parameters of the copula functions have been the Maximum Likelihood Estimator (MLE) and the Inference Functions for Margins (IFM) methods. Archimedean copulas are one of the most important classes of copulas that are widely used in both finance and insurance for modelling dependent risks. However, simulating multivariate Archimedean copulas has always been a difficult task as the number of dimensions increases. The assessment of capital requirements has always been an important application of stochastic modelling. Capital requirements can vary significantly depending on the model adopted. Several professional bodies have recently discussed the concept of dependencies between insurance risks. They suggest that insurers should use a technique based on copulas to describe the dependence of risks within an insurance company in the context of solvency assessment. The first contribution of this thesis is to provide an insight into the efficiency of parameter estimation methods. This thesis uses numerical experiments to assess the performance of the two common approaches. The second contribution of this thesis is to present a new algorithm to simulate multivariate Exchangeable Archimedean copulas. This algorithm provides a practical solution for simulating one-parameter multivariate Archimedean copulas. Numerical experiments are used to apply this algorithm to determine the "additional" economic capital for an insurance company with multiple lines of business that wants to expand its business by adding another line of business and where the businesses are dependent. The third contribution of this thesis is to quantify the impact of the choice of copulas on the solvency measure of a general insurer within a Dynamic Financial Analysis modelling framework. The results of our experiments provide important guidance for the capital assessment for general insurers.
3

Probabilistic settlement analysis for embankments using preloading without surcharge

Escher, Karl January 2022 (has links)
Preloading without a surcharge is a common method for ground improvement. Thereare however uncertainties related to the number of site investigations and the partialfactor method has been identified as a problem. This thesis proposes a probabilisticdesign approach, using a Monte Carlo simulation to calculate the failure probabilityin the serviceability limit state for preloading without a surcharge. The methodwas applied to a case where the possibility of using preloading without a surchargewas determined. A parameter influence and sensitivity analysis were performed todetermine what parameters were most important for the calculation. Problems withthe generation of random samples for the parameters; preconsolidation pressure andlimit pressure were identified, and four different methods of generating the randomsamples were tested, and discussed.The failure probability was calculated as a function of preloading time which wasused to determine what preloading time is needed to fall below the acceptable failureprobability of 5%. The required preloading time was found to be 580 days. Themost important parameters were found to be preconsolidation pressure, the modulusM0 and the coefficient of vertical consolidation.The proposed method is working and has several advantages, among them are theability to calculate the failure probability and the compatibility with the observationalmethod. The model uncertainty has been discussed, and a general commentis that with more research can the model uncertainty be decreased. Only 1D consolidationis considered in the method, this simplification is very practical as 2D and3D effects often can be neglected.

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