176 results on '"Loisel, Stéphane"'
Search Results
2. Bayesian model averaging for mortality forecasting using leave-future-out validation
- Author
-
Barigou, Karim, Goffard, Pierre-Olivier, Loisel, Stéphane, and Salhi, Yahia
- Subjects
Statistics - Applications - Abstract
Predicting the evolution of mortality rates plays a central role for life insurance and pension funds.Various stochastic frameworks have been developed to model mortality patterns taking into account the main stylized facts driving these patterns. However, relying on the prediction of one specific model can be too restrictive and lead to some well documented drawbacks including model misspecification, parameter uncertainty and overfitting. To address these issues we first consider mortality modelling in a Bayesian Negative-Binomial framework to account for overdispersion and the uncertainty about the parameter estimates in a natural and coherent way. Model averaging techniques are then considered as a response to model misspecifications. In this paper, we propose two methods based on leave-future-out validation which are compared to the standard Bayesian model averaging (BMA) based on marginal likelihood. An intensive numerical study is carried out over a large range of simulation setups to compare the performances of the proposed methodologies. An illustration is then proposed on real-life mortality datasets which includes a sensitivity analysis to a Covid-type scenario. Overall, we found that both methods based on out-of-sample criterion outperform the standard BMA approach in terms of prediction performance and robustness.
- Published
- 2021
3. Quickest detection in practice in presence of seasonality: An illustration with call center data
- Author
-
Laub, Patrick J., Karoui, Nicole El, Loisel, Stéphane, and Salhi, Yahia
- Subjects
Statistics - Applications ,Statistics - Computation - Abstract
In this chapter, we explain how quickest detection algorithms can be useful for risk management in presence of seasonality. We investigate the problem of detecting fast enough cases when a call center will need extra staff in a near future with a high probability. We illustrate our findings on real data provided by a French insurer. We also discuss the relevance of the CUSUM algorithm and of some machine-learning type competitor for this applied problem.
- Published
- 2020
4. Applying economic measures to lapse risk management with machine learning approaches
- Author
-
Loisel, Stéphane, Piette, Pierrick, and Tsai, Jason
- Subjects
Statistics - Applications - Abstract
Modeling policyholders lapse behaviors is important to a life insurer since lapses affect pricing, reserving, profitability, liquidity, risk management, as well as the solvency of the insurer. Lapse risk is indeed the most significant life underwriting risk according to European Insurance and Occupational Pensions Authority's Quantitative Impact Study QIS5. In this paper, we introduce two advanced machine learning algorithms for lapse modeling. Then we evaluate the performance of different algorithms by means of classical statistical accuracy and profitability measure. Moreover, we adopt an innovative point of view on the lapse prediction problem that comes from churn management. We transform the classification problem into a regression question and then perform optimization, which is new for lapse risk management. We apply different algorithms to a large real-world insurance dataset. Our results show that XGBoost and SVM outperform CART and logistic regression, especially in terms of the economic validation metric. The optimization after transformation brings out significant and consistent increases in economic gains.
- Published
- 2019
5. Partially Schur-constant models
- Author
-
Castañer, Anna, Claramunt, M. Mercè, Lefèvre, Claude, and Loisel, Stéphane
- Published
- 2019
- Full Text
- View/download PDF
6. French coastal network for carbonate system monitoring: the CocoriCO2 dataset.
- Author
-
Petton, Sébastien, Pernet, Fabrice, Le Roy, Valérian, Huber, Matthias, Martin, Sophie, Macé, Éric, Bozec, Yann, Loisel, Stéphane, Rimmelin-Maury, Peggy, Grossteffan, Émilie, Repecaud, Michel, Quemener, Loïc, Retho, Michael, Manac'h, Soazig, Papin, Mathias, Pineau, Philippe, Lacoue-Labarthe, Thomas, Deborde, Jonathan, Costes, Louis, and Polsenaere, Pierre
- Subjects
ATMOSPHERIC carbon dioxide ,GROUNDWATER monitoring ,SENSOR networks ,OCEAN acidification ,MARINE ecology ,CARBON dioxide - Abstract
Since the beginning of the industrial revolution, atmospheric carbon dioxide (CO 2) concentrations have risen steadily and have induced a decrease of the averaged surface ocean pH by 0.1 units, corresponding to an increase in ocean acidity of about 30 %. In addition to ocean warming, ocean acidification poses a tremendous challenge to some marine organisms, especially calcifiers. The need for long-term oceanic observations of pH and temperature is a key element to assess the vulnerability of marine communities and ecosystems to these pressures. Nearshore productive environments, where a large majority of shellfish farming activities are conducted, are known to present pH levels as well as amplitudes of daily and seasonal variations that are much larger than those observed in the open ocean. Yet, to date, there are very few coastal observation sites where these parameters are measured simultaneously and at high frequency. To bridge this gap, an observation network was initiated in 2021 in the framework of the CocoriCO 2 project. Six sites were selected along the French Atlantic and Mediterranean coastlines based on their importance in terms of shellfish production and the presence of high- and low-frequency monitoring activities. At each site, autonomous pH sensors were deployed, both inside and outside shellfish production areas, next to high-frequency CTD (conductivity–temperature–depth) probes operated through two operating monitoring networks. pH sensors were set to an acquisition rate of 15 min, and discrete seawater samples were collected biweekly in order to control the quality of pH data (laboratory spectrophotometric measurements) as well as to measure total alkalinity and dissolved inorganic carbon concentrations for full characterization of the carbonate system. While this network has been up and running for more than 2 years, the acquired dataset has already revealed important differences in terms of pH variations between monitored sites related to the influence of diverse processes (freshwater inputs, tides, temperature, biological processes). Data are available at 10.17882/96982 (Petton et al., 2023a). [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
7. MINIMAX OPTIMALITY IN ROBUST DETECTION OF A DISORDER TIME IN DOUBLY-STOCHASTIC POISSON PROCESSES
- Author
-
Karoui, Nicole El, Loisel, Stéphane, and Salhi, Yahia
- Published
- 2017
8. On finite exchangeable sequences and their dependence
- Author
-
Lefèvre, Claude, Loisel, Stéphane, and Utev, Sergey
- Published
- 2017
- Full Text
- View/download PDF
9. On the Devylder–Goovaerts Conjecture in Ruin Theory
- Author
-
Loisel, Stéphane, primary and Minier, Charles, additional
- Published
- 2023
- Full Text
- View/download PDF
10. A polynomial expansion to approximate the ultimate ruin probability in the compound Poisson ruin model
- Author
-
Goffard, Pierre-Olivier, Loisel, Stéphane, and Pommeret, Denys
- Published
- 2016
- Full Text
- View/download PDF
11. French coastal network for carbonate system monitoring: The CocoriCO2 dataset.
- Author
-
Petton, Sébastien, Pernet, Fabrice, Roy, Valérian Le, Huber, Matthias, Martin, Sophie, Macé, Éric, Bozec, Yann, Loisel, Stéphane, Rimmelin-Maury, Peggy, Grossteffan, Émilie, Repecaud, Michel, Quemener, Loïc, Retho, Michael, Manac’h, Soazig, Papin, Mathias, Pineau, Philippe, LacoueLabarthe, Thomas, Deborde, Jonathan, Costes, Louis, and Polsenaere, Pierre
- Subjects
ATMOSPHERIC carbon dioxide ,GROUNDWATER monitoring ,OCEAN acidification ,SENSOR networks ,MARINE ecology ,CARBONATES - Abstract
Since the beginning of the industrial revolution, atmospheric carbon dioxide (CO
2 ) concentrations have risen steadily and have induced a decrease of the averaged surface ocean pH by 0.1 units, corresponding to an increase in ocean acidity of about 30 %. In addition to ocean warming, ocean acidification poses a tremendous challenge to some marine organisms, especially calcifiers. The need for long-term oceanic observations of pH and temperature is a key element to assess the vulnerability of marine communities and ecosystems to these pressures. Nearshore productive environments, where a large majority of shellfish farming activities are conducted, are known to present pH levels as well as amplitudes of daily and seasonal variations that are much larger than those observed in the open ocean. Yet, to date, there are very few coastal observation sites where these parameters are measured simultaneously and at high frequency. To bridge this gap, an observation network was initiated in 2021 in the framework of the CocoriCO2 project. Six sites were selected along the French Atlantic and Mediterranean coastlines based on their importance in terms of shellfish production and the presence of high- and low-frequency monitoring activities. At each site, autonomous pH sensors were deployed both inside and outside shellfish production areas, next to high-frequency CTD (conductivity- temperature-depth) probes operated through two operating monitoring networks. pH sensors were set to an acquisition rate of 15 min and discrete seawater samples were collected biweekly in order to control the quality of pH data (laboratory spectrophotometric measurements) as well as to measure total alkalinity and dissolved inorganic carbon concentrations for full characterization of the carbonate system. While this network has been up and running for more than two years, the acquired dataset has already revealed important differences in terms of pH variations between monitored sites related to the influence of diverse processes (freshwater inputs, tides, temperature, biological processes). [ABSTRACT FROM AUTHOR]- Published
- 2023
- Full Text
- View/download PDF
12. Convex extrema for nonincreasing discrete distributions: Effects of convexity constraints
- Author
-
Kacem, Manel, Lefèvre, Claude, and Loisel, Stéphane
- Published
- 2015
- Full Text
- View/download PDF
13. Competition among non-life insurers under solvency constraints: A game-theoretic approach
- Author
-
Dutang, Christophe, Albrecher, Hansjoerg, and Loisel, Stéphane
- Published
- 2013
- Full Text
- View/download PDF
14. ON MULTIPLY MONOTONE DISTRIBUTIONS, CONTINUOUS OR DISCRETE, WITH APPLICATIONS
- Author
-
LEFÈVRE, CLAUDE and LOISEL, STÉPHANE
- Published
- 2013
15. Risk adjustment under IFRS 17: An adaptation of Solvency 2 one-year aggregation into an ultimate view framework
- Author
-
El Alami, Tachfine, Devineau, Laurent, Loisel, Stéphane, and El Alami, Tachfine
- Subjects
Risk Aggregation ,Ultimate view ,Time diversification ,[QFIN.RM] Quantitative Finance [q-fin]/Risk Management [q-fin.RM] ,Risk Adjustment ,IFRS 17 ,Solvency 2 ,[SHS.ECO] Humanities and Social Sciences/Economics and Finance ,Correlation - Abstract
The standard IFRS 17 introduces a risk adjustment (RA) to reflect the compensation the insurance entity requires for bearing the uncertainty associated with nonfinancial risks. The risk adjustment is one of the main components in IFRS 17 disclosures and is a factor that impacts strongly IFRS 17 P&L and balance sheet as well as their evolution over a time horizon. IFRS 17 does not prescribe any specific techniques for calculation methodologies; insurance entities are free to adopt their own assessment while meeting several qualitative rules to ensure their consistency. This paper focuses on the recommendations of paragraph §B88 stating that the risk adjustment is required to reflect the diversification benefit of bearing the risk. We suggest a method for aggregating elementary RA (per risk and/or per Line of Business) based on the Solvency 2 elliptic aggregation. We introduce the concept of ultimate correlation as opposed to Solvency 2 one-year correlation and provide a theoretical bridge between both depending on a time diversification parameter. We explore correlation structures involving this time diversification and discuss analytical properties in terms of possible correlations values and the resulting impact on the aggregated RA features.
- Published
- 2022
16. From deterministic to stochastic surrender risk models: Impact of correlation crises on economic capital
- Author
-
Loisel, Stéphane and Milhaud, Xavier
- Published
- 2011
- Full Text
- View/download PDF
17. Differentiation of Some Functionals of Risk Processes, and Optimal Reserve Allocation
- Author
-
Loisel, Stéphane
- Published
- 2005
18. Predicted Impacts of Booster, Immunity Decline, Vaccination Strategies, and Non-Pharmaceutical Interventions on COVID-19 Outcomes in France.
- Author
-
Pageaud, Simon, Eyraud-Loisel, Anne, Bertoglio, Jean-Pierre, Bienvenüe, Alexis, Leboisne, Nicolas, Pothier, Catherine, Rigotti, Christophe, Ponthus, Nicolas, Gauchon, Romain, Gueyffier, François, Vanhems, Philippe, Iwaz, Jean, Loisel, Stéphane, and Roy, Pascal
- Subjects
VACCINATION of children ,BOOSTER vaccines ,VACCINATION ,COVID-19 ,IMMUNITY - Abstract
The major economic and health consequences of COVID-19 called for various protective measures and mass vaccination campaigns. A previsional model was used to predict the future impacts of various measure combinations on COVID-19 mortality over a 400-day period in France. Calibrated on previous national hospitalization and mortality data, an agent-based epidemiological model was used to predict individual and combined effects of booster doses, vaccination of refractory adults, and vaccination of children, according to infection severity, immunity waning, and graded non-pharmaceutical interventions (NPIs). Assuming a 1.5 hospitalization hazard ratio and rapid immunity waning, booster doses would reduce COVID-19-related deaths by 50–70% with intensive NPIs and 93% with moderate NPIs. Vaccination of initially-refractory adults or children ≥ 5 years would half the number of deaths whatever the infection severity or degree of immunity waning. Assuming a 1.5 hospitalization hazard ratio, rapid immunity waning, moderate NPIs and booster doses, vaccinating children ≥ 12 years, ≥ 5 years, and ≥ 6 months would result in 6212, 3084, and 3018 deaths, respectively (vs. 87,552, 64,002, and 48,954 deaths without booster, respectively). In the same conditions, deaths would be 2696 if all adults and children ≥ 12 years were vaccinated and 2606 if all adults and children ≥ 6 months were vaccinated (vs. 11,404 and 3624 without booster, respectively). The model dealt successfully with single measures or complex combinations. It can help choosing them according to future epidemic features, vaccination extensions, and population immune status. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
- View/download PDF
19. In situ estimates of kelp forest productivity in macro‐tidal environments
- Author
-
White, Lydia, primary, Loisel, Stéphane, additional, Sevin, Laure, additional, and Davoult, Dominique, additional
- Published
- 2021
- Full Text
- View/download PDF
20. Sensitivity analysis and density estimation for finite-time ruin probabilities
- Author
-
Loisel, Stéphane and Privault, Nicolas
- Published
- 2009
- Full Text
- View/download PDF
21. On the measure of risks in a ruin context and the measure of dependence.
- Author
-
Trufin, Julien, Verdebout, Thomas, Lefèvre, Claude, Denuit, Michel, Loisel, Stéphane, Zuyderhoff, Pierre, Trufin, Julien, Verdebout, Thomas, Lefèvre, Claude, Denuit, Michel, Loisel, Stéphane, and Zuyderhoff, Pierre
- Abstract
For an insurance company, one of the main objectives in risk management is to assess the risk associated with an insurance portfolio. In insurance mathematics, ruin theory is a traditional tool for performing such an evaluation. In the context of this theory, the time evolution of the reserve of an insurance company is modelled by a long-term risk process. In order to assess the riskiness of such a process, an appropriate risk measure is needed. However, there is no single number that captures all the characteristics of the risk associated with the process. Hence, there is a need to develop multiple risk measures, and to select an appropriate risk measure depending on the context in mind. Another issue related to many risk management situations is the need to properly measure the dependency between two random variables. Standard dependence measures include Spearman rank correlation coefficient and Kendall rank correlation coefficient. In this context, the case where at least one of the random variables is discrete is qualitatively different from the continuous case. This situation occurs, for example, when one wishes to assess the dependence between the annual number of claims for policyholders who experienced at least one claim and the average claim severity. In this case, the results of dependency measures need to be interpreted differently since small values of these measures may actually support strong dependence. This thesis consists of two parts. The first part is devoted to ruin theory. Although ruin theory is the subject of abundant literature, questions remain unanswered. We aim to give answers to questions related to computation, properties and applications of ruin-based risk measures within both continuous and discrete-time models. In the second part, we derive bounds on Spearman's rho in case of at least one random variable is discrete. A motivation for this is given in terms of applications of practical relevance., Doctorat en Sciences, info:eu-repo/semantics/nonPublished
- Published
- 2021
22. Optimal prevention of large risks with two types of claims
- Author
-
Gauchon, Romain, Loisel, Stéphane, Rullière, Jean Louis, Trufin, Julien, Gauchon, Romain, Loisel, Stéphane, Rullière, Jean Louis, and Trufin, Julien
- Abstract
In this paper, we propose and study a risk model with two types of claims in which the insurer may invest into a prevention plan which decreases the intensity of large claims without impacting the small claims. We identify a necessary and sufficient condition for insurers to use prevention if there is no surplus. If, in addition, the severity of large claims dominates that of small claims by the harmonic mean residual life (HMRL) order, insurers invest more in prevention in the presence of a surplus. Finally, we characterize the asymptotic optimal prevention strategy when the initial surplus tends to infinity in the two main cases where both claim types are light-tailed and where one of them is light-tailed and the other one is heavy-tailed., SCOPUS: ar.j, info:eu-repo/semantics/published
- Published
- 2021
23. A marine biodiversity observation network for genetic monitoring of hard-bottom communities (ARMS-MBON)
- Author
-
Obst, Matthias, Exter, Katrina, Allcock, A. Louise, Arvanitidis, Christos, Axberg, Alizz, Bustamante, Maria, Cancio, Ibon, Carreira Flores, Diego, Chatzinikolaou, Eva, Chatzigeorgiou, Giorgos, Chrismas, Nathan, Clark, Melody S., Comtet, Thierry, Dailianis, Thanos, Davies, Neil, Deneudt, Klaas, Diaz de Cerio, Oihane, Fortič, Ana, Gerovasileiou, Vasilis, Hablützel, Pascal I., Keklikoglou, Kleoniki, Kotoulas, Georgios, Lasota, Rafal, Leite, Barbara R., Loisel, Stéphane, Lévêque, Laurent, Levy, Liraz, Malachowicz, Magdalena, Mavrič, Borut, Meyer, Christopher, Mortelmans, Jonas, Norkko, Joanna, Pade, Nicolas, Power, Anne Marie, Ramšak, Andreja, Reiss, Henning, Solbakken, Jostein, Staehr, Peter A., Sundberg, Per, Thyrring, Jakob, Souza Troncoso, Jesús, Viard, Frédérique, Wenne, Roman, Yperifanou, Eleni Ioanna, Zbawicka, Malgorzata, Pavloudi, Christina, Institut des Sciences de l'Evolution de Montpellier (UMR ISEM), École pratique des hautes études (EPHE), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Montpellier (UM)-Centre de Coopération Internationale en Recherche Agronomique pour le Développement (Cirad)-Centre National de la Recherche Scientifique (CNRS)-Institut de recherche pour le développement [IRD] : UR226, Centre de Coopération Internationale en Recherche Agronomique pour le Développement (Cirad)-École Pratique des Hautes Études (EPHE), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Montpellier (UM)-Institut de recherche pour le développement [IRD] : UR226-Centre National de la Recherche Scientifique (CNRS), European Commission, Biological stations, Ecosystems and Environment Research Programme, Tvärminne Benthic Ecology Team, Marine Ecosystems Research Group, and Tvärminne Zoological Station
- Subjects
European Marine Biological Resource Centre (EMBRC) ,Matematikk og Naturvitenskap: 400::Zoologiske og botaniske fag: 480::Marinbiologi: 497 [VDP] ,2417.13 Ecología Vegetal ,gap ,2510.04 Botánica Marina ,Matematikk og Naturvitenskap: 400::Geofag: 450 [VDP] ,Genomic Observatories ,Essential Biodiversity Variables (EBVs) ,benthic invertebrates ,non-indigenous species (NIS) ,1181 Ecology, evolutionary biology ,Matematikk og Naturvitenskap: 400::Zoologiske og botaniske fag: 480::Økologi: 488 [VDP] ,2401 Biología Animal (Zoología) ,samples ,Marine Strategy Framework Directive (MSFD) ,Essential Ocean Variables (EOVs) ,marine biodiversity assessment ,[SDE.BE]Environmental Sciences/Biodiversity and Ecology ,1172 Environmental sciences ,ComputingMilieux_MISCELLANEOUS - Abstract
Marine hard-bottom communities are undergoing severe change under the influence of multiple drivers, notably climate change, extraction of natural resources, pollution and eutrophication, habitat degradation, and invasive species. Monitoring marine biodiversity in such habitats is, however, challenging as it typically involves expensive, non-standardized, and often destructive sampling methods that limit its scalability. Differences in monitoring approaches furthermore hinders inter-comparison among monitoring programs. Here, we announce a Marine Biodiversity Observation Network (MBON) consisting of Autonomous Reef Monitoring Structures (ARMS) with the aim to assess the status and changes in benthic fauna with genomic-based methods, notably DNA metabarcoding, in combination with image-based identifications. This article presents the results of a 30-month pilot phase in which we established an operational and geographically expansive ARMS-MBON. The network currently consists of 20 observatories distributed across European coastal waters and the polar regions, in which 134 ARMS have been deployed to date. Sampling takes place annually, either as short-term deployments during the summer or as long-term deployments starting in spring. The pilot phase was used to establish a common set of standards for field sampling, genetic analysis, data management, and legal compliance, which are presented here. We also tested the potential of ARMS for combining genetic and image-based identification methods in comparative studies of benthic diversity, as well as for detecting non-indigenous species. Results show that ARMS are suitable for monitoring hard-bottom environments as they provide genetic data that can be continuously enriched, re-analyzed, and integrated with conventional data to document benthic community composition and detect non-indigenous species. Finally, we provide guidelines to expand the network and present a sustainability plan as part of the European Marine Biological Resource Centre (www.embrc.eu). This ARMS-MBON network is funded by the infrastructure programs ASSEMBLE Plus (grant no. 730984) and the European Marine Biological Resource Centre, EMBRC. Both programs establish and maintain the core network and provide services and consultation for deployment, sample processing, sequencing, data management, and analysis. Funding for ARMS observatories in the North Sea Region was provided by the INTERREG project GEANS (North Sea Program of the European Regional Development Fund of the European Union) and the Swedish Agency for Marine and Water Management (grant no. 31812019), and the Flanders LifeWatch contribution (Research Foundation Flanders grant I000819N). The ARMS observatory in Roscoff also received support from the Aquanis 2.0 project (FONDATION Total). Data management and analysis was funded by Swedish LifeWatch grant from the Swedish Research council (grant no. 2017-00634) as well as the EOSC NORDIC project (grant no. 857652). Guiding documents to obtain ABS clearance for access to genetic resources were developed in the framework of projects INTERREG EBB (EAPA_501/2016) and H2020 EOSC-Life (grant no. 824087).
- Published
- 2020
24. Locality in time of the European insurance regulation 'risk-neutral' valuation framework, a pre-and post-Covid analysis and further developments
- Author
-
Borel-Mathurin, Fabrice, El Karoui, Nicole, Loisel, Stéphane, Vedani, Julien, Autorité de Contrôle Prudentiel et de Résolution (ACPR), Autorité de Contrôle Prudentiel et de Résolution, Laboratoire de Probabilités, Statistiques et Modélisations (LPSM (UMR_8001)), Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP), Université Paris Diderot - Paris 7 (UPD7)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de Sciences Actuarielle et Financière (SAF), Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon, and Vedani, Julien
- Subjects
[QFIN.RM] Quantitative Finance [q-fin]/Risk Management [q-fin.RM] ,[QFIN.RM]Quantitative Finance [q-fin]/Risk Management [q-fin.RM] - Abstract
The so-called market-consistency of the European life insurance valuation as shaped by regulation guidelines embeds numerous theoretical and practical misstatements. Since El Karoui et al. (2017) the manipulation risk induced by the framework imprecision and, in particular, its high dependency to regulatory and non-regulatory calibration data is clear. In this paper we update some results and analysis of El Karoui et al. (2017) using data from a more recent "classical" year (2017) and from an exceptional year (first quarter of 2020, with Covid-19 effects), and test additional sensitivities. Based on the updated values we obtain up to-45% in the V IF estimates values depending on the swaption implied volatilities matrix used to calibrate the interest rates model. Then trying different calibration sets we obtain up to 105% difference. In parallel, we see that using 3-month averages to calibrate Economic Scenario Generators do not make effects of crises like Covid-19 disappear. We then address the "simulation seed" setting issue, and the interest and limits of keeping the same seed when estimating and comparing economic valuations, be it on horizontal (comparing valuations through time) or vertical (studying sensitivities at the same date) analysis. We finally open our study to propose various tools for a better risk management of economic scenarios and valuation, through a better understanding of Asset-Liability Management models.
- Published
- 2020
25. Basis Risk Management in an Index-Based Insurance Framework under Randomly Scaled Uncertainty
- Author
-
Lefèvre, Claude, Loisel, Stéphane, Montesinos, Pierre, Département de Mathématique [Bruxelles] (ULB), Faculté des Sciences [Bruxelles] (ULB), Université libre de Bruxelles (ULB)-Université libre de Bruxelles (ULB), Laboratoire de Sciences Actuarielle et Financière (SAF), Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon, and Montesinos, Pierre
- Subjects
Random scaling ,[MATH.MATH-PR]Mathematics [math]/Probability [math.PR] ,[MATH.MATH-PR] Mathematics [math]/Probability [math.PR] ,ERM ,Basis risk ,[SHS] Humanities and Social Sciences ,s-convex extrema ,Index-based insurance ,[SHS]Humanities and Social Sciences - Abstract
This paper is concerned with the quantification of basis risk in index-based insurance products using randomly scaled variables. To this extent, we first discuss the shape, the unimodality and the symmetry of randomly scaled variables depending on the distribution of the random scaling factor using Mellin transform. We explicitly obtain the distribution of a randomly scaled variable when the random scaling factor is either uniformly distributed or of Beta type. We then determine s-convex extremal distributions for randomly scaled variables and discuss the way of comparing it. Next, we define an Enterprise Risk Management framework that relies on randomly scaled variables to assess basis risk, introducing the class of generalized penalty functions. This ERM framework allows for setting up basis risk limits to eventually determine a Basis Risk Capital Requirement. The results are illustrated with particular cases that carefully challenge the methodology.
- Published
- 2020
26. Bounding basis risk using s-convex orders on Beta-unimodal distributions
- Author
-
Lefèvre, Claude, Loisel, Stéphane, Montesinos, Pierre, Département de Mathématique [Bruxelles] (ULB), Faculté des Sciences [Bruxelles] (ULB), Université libre de Bruxelles (ULB)-Université libre de Bruxelles (ULB), Laboratoire de Sciences Actuarielle et Financière (SAF), Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon, and Montesinos, Pierre
- Subjects
[MATH.MATH-PR]Mathematics [math]/Probability [math.PR] ,[MATH.MATH-PR] Mathematics [math]/Probability [math.PR] ,s-convex stochas- tic orders ,Risk management ,Beta-unimodality ,[SHS.GESTION]Humanities and Social Sciences/Business administration ,Basis risk ,[MATH] Mathematics [math] ,s-convex extrema ,Parametric index ,[MATH]Mathematics [math] ,[SHS.GESTION] Humanities and Social Sciences/Business administration - Abstract
This paper is concerned with properties of Beta-unimodal distributions and their use to assess the basis risk inherent to index-based insurance or reinsurance contracts. To this extent, we first characterize s-convex stochastic orders for Beta-unimodal distributions in terms of the Weyl fractional integral. We then determine s-convex extrema for such distributions , focusing in particular on the cases s = 2, 3, 4. Next, we define an Enterprise Risk Management framework that relies on Beta-unimodality to assess these hedge imperfections , introducing several penalty functions and worst case scenarios. Some of the results obtained are illustrated numerically via a representative catastrophe model.
- Published
- 2020
27. MODELISATION DES CHOCS BIOMERIQUES EN ASSURANCE DE PERSONNES
- Author
-
Loisel, Stéphane, Olympio, Anani, Zozime, Jérémy, Laboratoire de Sciences Actuarielle et Financière (SAF), Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon, and OLYMPIO, Anani Ayodele
- Subjects
[QFIN.RM] Quantitative Finance [q-fin]/Risk Management [q-fin.RM] ,[QFIN.RM]Quantitative Finance [q-fin]/Risk Management [q-fin.RM] - Published
- 2020
28. Health-policyholder clustering using health consumption
- Author
-
Gauchon, Romain, Loisel, Stéphane, Rullière, Jean-Louis, and Gauchon, Romain
- Subjects
Health insurance claims databases ,Kohonen self-organizing map ,Prevention ,Clustering Algorithm ,[QFIN.RM] Quantitative Finance [q-fin]/Risk Management [q-fin.RM] ,[INFO.INFO-LG] Computer Science [cs]/Machine Learning [cs.LG] ,Non negative Matrix Factorization NMF - Abstract
On paper, prevention appears to be a good complement to health insurance. However, its implementation is often costly. To maximize the impact and efficiency of prevention plans these should target particular groups of policyholders. In this article, we propose a way of clustering policyholders that could be a starting point for the targeting of prevention plans. This two-step method mainly classifies using policyholder health consumption. This dimension is first reduced using a Nonnegative matrix factorization algorithm, producing intermediate health-product clusters. We then cluster using Kohonen's map algorithm. This leads to a natural visualization of the results, allowing the simple comparison of results from different databases. We apply our method to two real health-insurer datasets. We carry out a number of tests (including tests on a text-mining database) of method stability and clustering ability. The method is shown to be stable, easily-understandable, and able to cluster most policyholders efficiently.
- Published
- 2020
29. A Marine Biodiversity Observation Network for Genetic Monitoring of Hard-Bottom Communities (ARMS-MBON)
- Author
-
Biología vegetal y ecología, Landaren biologia eta ekologia, Obst, Matthias, Exter, Katrina, Allcock, A. Louise, Arvanitidis, Christos, Axberg, Alizz, Bustamante González, María, Cancio Uriarte, Ibon, Carreira Flores, Diego, Chatzinikolaou, Eva, Chatzigeorgiou, Giorgos, Chrismas, Nathan, Clark, Melody S., Comtet, Thierry, Dailianis, Thanos, Davies, Neil, Deneudt, Klaas, Diaz de Cerio, Oihane, Fortič, Ana, Gerovasileiou, Vasilis, Hablützel, Pascal I., Keklikoglou, Kleoniki, Kotoulas, Georgios, Lasota, Rafal, Leite, Barbara R., Loisel, Stéphane, Lévêque, Laurent, Levy, Liraz, Malachowicz, Magdalena, Mavrič, Borut, Meyer, Christopher, Mortelmans, Jonas, Norkko, Joanna, Pade, Nicolas, Power, Anne Marie, Ramšak, Andreja, Reiss, Henning, Solbakken, Jostein, Staehr, Peter A., Sundberg, Per, Thyrring, Jakob, Troncoso, Jesus S., Viard, Frédérique, Wenne, Roman, Yperifanou, Eleni Ioanna, Zbawicka, Malgorzata, Pavloudi, Christina, Biología vegetal y ecología, Landaren biologia eta ekologia, Obst, Matthias, Exter, Katrina, Allcock, A. Louise, Arvanitidis, Christos, Axberg, Alizz, Bustamante González, María, Cancio Uriarte, Ibon, Carreira Flores, Diego, Chatzinikolaou, Eva, Chatzigeorgiou, Giorgos, Chrismas, Nathan, Clark, Melody S., Comtet, Thierry, Dailianis, Thanos, Davies, Neil, Deneudt, Klaas, Diaz de Cerio, Oihane, Fortič, Ana, Gerovasileiou, Vasilis, Hablützel, Pascal I., Keklikoglou, Kleoniki, Kotoulas, Georgios, Lasota, Rafal, Leite, Barbara R., Loisel, Stéphane, Lévêque, Laurent, Levy, Liraz, Malachowicz, Magdalena, Mavrič, Borut, Meyer, Christopher, Mortelmans, Jonas, Norkko, Joanna, Pade, Nicolas, Power, Anne Marie, Ramšak, Andreja, Reiss, Henning, Solbakken, Jostein, Staehr, Peter A., Sundberg, Per, Thyrring, Jakob, Troncoso, Jesus S., Viard, Frédérique, Wenne, Roman, Yperifanou, Eleni Ioanna, Zbawicka, Malgorzata, and Pavloudi, Christina
- Abstract
Marine hard-bottom communities are undergoing severe change under the influence of multiple drivers, notably climate change, extraction of natural resources, pollution and eutrophication, habitat degradation, and invasive species. Monitoring marine biodiversity in such habitats is, however, challenging as it typically involves expensive, non-standardized, and often destructive sampling methods that limit its scalability. Differences in monitoring approaches furthermore hinders inter-comparison among monitoring programs. Here, we announce a Marine Biodiversity Observation Network (MBON) consisting of Autonomous Reef Monitoring Structures (ARMS) with the aim to assess the status and changes in benthic fauna with genomic-based methods, notably DNA metabarcoding, in combination with image-based identifications. This article presents the results of a 30-month pilot phase in which we established an operational and geographically expansive ARMS-MBON. The network currently consists of 20 observatories distributed across European coastal waters and the polar regions, in which 134 ARMS have been deployed to date. Sampling takes place annually, either as short-term deployments during the summer or as long-term deployments starting in spring. The pilot phase was used to establish a common set of standards for field sampling, genetic analysis, data management, and legal compliance, which are presented here. We also tested the potential of ARMS for combining genetic and image-based identification methods in comparative studies of benthic diversity, as well as for detecting non-indigenous species. Results show that ARMS are suitable for monitoring hard-bottom environments as they provide genetic data that can be continuously enriched, re-analyzed, and integrated with conventional data to document benthic community composition and detect non-indigenous species. Finally, we provide guidelines to expand the network and present a sustainability plan as part of the European Marine Biol
- Published
- 2020
30. Optimal prevention strategies in the classical risk model
- Author
-
Gauchon, Romain, Loisel, Stéphane, Rullière, Jean Louis, Trufin, Julien, Gauchon, Romain, Loisel, Stéphane, Rullière, Jean Louis, and Trufin, Julien
- Abstract
In this paper, we propose and study a first risk model in which the insurer may invest into a prevention plan which decreases claim intensity. We determine the optimal prevention investment for different risk indicators. In particular, we show that the prevention amount minimizing the ruin probability maximizes the adjustment coefficient in the classical ruin model with prevention, as well as the expected dividends until ruin in the model with dividends. We also show that the optimal prevention strategy is different if one aims at maximizing the average surplus at a fixed time horizon. A sensitivity analysis is carried out. We also prove that our results can be extended to the case where prevention starts to work only after a minimum prevention level threshold., SCOPUS: ar.j, info:eu-repo/semantics/published
- Published
- 2020
31. Parsimonious Predictive Mortality Modeling by Regularization and Cross-Validation with and without Covid-Type Effect
- Author
-
Barigou, Karim, primary, Loisel, Stéphane, additional, and Salhi, Yahia, additional
- Published
- 2020
- Full Text
- View/download PDF
32. Obfuscation and Honesty Experimental Evidence on Insurance Demand with Multiple Distribution Channels
- Author
-
Mouminoux, Claire, Rullière, Jean-Louis, Loisel, Stéphane, Laboratoire de Sciences Actuarielle et Financière (SAF), Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon, and Mouminoux, Claire
- Subjects
honesty ,search costs ,intermediation ,distribution channels ,[SHS.GESTION]Humanities and Social Sciences/Business administration ,behavioral economics ,[SHS.GESTION] Humanities and Social Sciences/Business administration ,[SHS.ECO] Humanities and Social Sciences/Economics and Finance ,[SHS.ECO]Humanities and Social Sciences/Economics and Finance ,obfuscation ,insurance - Abstract
This paper aims to shed light on the dilemma faced by insurance purchasers faced with multiple distribution channels. Should the consumer herself choose from a large set of insurance policies or rather delegate a part her decision to an intermediary who is more or less honest? We consider decisions based on a number of real-world insurance distribution channels with different information frames. Beliefs about intermediary honesty are the main determinants of individual choice. In addition, the obfuscation of information is the main source of inefficiency in decision-making, particularly regarding the characteristics of the insurance contracts chosen by consumers.
- Published
- 2018
33. A quantum-type approach to non-life insurance risk modelling
- Author
-
Lefèvre, Claude, Loisel, Stéphane, Tamturk, Muhsin, Utev, Sergey, Lefèvre, Claude, Loisel, Stéphane, Tamturk, Muhsin, and Utev, Sergey
- Abstract
A quantum mechanics approach is proposed to model non-life insurance risks and to compute the future reserve amounts and the ruin probabilities. The claim data, historical or simulated, are treated as coming from quantum observables and analyzed with traditional machine learning tools. They can then be used to forecast the evolution of the reserves of an insurance company. The following methodology relies on the Dirac matrix formalism and the Feynman path-integral method., SCOPUS: ar.j, info:eu-repo/semantics/published
- Published
- 2018
34. Minimax Optimality in Robust Detection of a Disorder Time in Poisson Rate
- Author
-
El Karoui, Nicole, Loisel, Stéphane, Salhi, Yahia, Laboratoire de Probabilités et Modèles Aléatoires (LPMA), Centre National de la Recherche Scientifique (CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Université Pierre et Marie Curie - Paris 6 (UPMC), Laboratoire de Sciences Actuarielle et Financière (SAF), Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon, ANR-13-BS01-0011,LoLitA,Modèles dynamiques pour la longévité humaine avec ajustements de style de vie(2013), Université Pierre et Marie Curie - Paris 6 (UPMC)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Loisel, Stéphane, and Blanc 2013 - Modèles dynamiques pour la longévité humaine avec ajustements de style de vie - - LoLitA2013 - ANR-13-BS01-0011 - Blanc 2013 - VALID
- Subjects
[MATH.MATH-PR]Mathematics [math]/Probability [math.PR] ,[MATH.MATH-PR] Mathematics [math]/Probability [math.PR] ,Poisson Process ,Change-Point,Robust Sequential Detection,Poisson Process ,Change-Point ,[QFIN.RM] Quantitative Finance [q-fin]/Risk Management [q-fin.RM] ,Robust Sequential Detection ,[QFIN.RM]Quantitative Finance [q-fin]/Risk Management [q-fin.RM] ,[SHS.ECO] Humanities and Social Sciences/Economics and Finance ,[SHS.ECO]Humanities and Social Sciences/Economics and Finance - Abstract
We consider the minimax quickest detection problem of an unobservable time of change in the rate of an inhomogeneous Poisson process. We seek a stopping rule that minimizes the robust Lorden criterion, formulated in terms of the number of events until detection, both for the worst-case delay and the false alarm constraint. In the Wiener case, such a problem has been solved using the so-called cumulative sums (cusum) strategy by Shiryaev [33, 35], or Moustakides [24] among others. In our setting, we derive the exact optimality of the cusum stopping rule by using finite variation calculus and elementary martingale properties to characterize the performance functions of the cusum stopping rule in terms of scale functions. These are solutions of some delayed differential equations that we solve elementarily. The case of detecting a decrease in the intensity is easy to study because the performance functions are continuous. In the case of an increase where the performance functions are not continuous, martingale properties require using a discontinuous local time. Nevertheless, from an identity relating the scale functions, the optimality of the cusum rule still holds. Finally, some numerical illustration are provided.
- Published
- 2015
35. A Quantum-Type Approach to Non-Life Insurance Risk Modelling
- Author
-
Lefèvre, Claude, primary, Loisel, Stéphane, additional, Tamturk, Muhsin, additional, and Utev, Sergey, additional
- Published
- 2018
- Full Text
- View/download PDF
36. Reevaluation of the capital charge in insurance after a large shock: empirical and theoretical views
- Author
-
UCL - SSH/IMMAQ/ISBA - Institut de Statistique, Biostatistique et Sciences Actuarielles, Borel-Mathurin, Fabrice, Loisel, Stéphane, Segers, Johan, UCL - SSH/IMMAQ/ISBA - Institut de Statistique, Biostatistique et Sciences Actuarielles, Borel-Mathurin, Fabrice, Loisel, Stéphane, and Segers, Johan
- Abstract
Motivated by the recent introduction of regulatory stress tests in the Solvency II framework, we study the impact of the re-estimation of the tail risk and of loss absorbing capacities on post-stress solvency ratios. Our contribution is threefold. First, we build the first stylized model for re-estimated solvency ratio in insurance. Second, this leads us to solve a new theoretical problem in statistics: what is the asymptotic impact of a record on the re-estimation of tail quantiles and tail probabilities for classical extreme value estimators? Third, we quantify the impact of the re-estimation of tail quantiles and of loss absorbing capacities on real-world solvency ratios thanks to regulator data from Banque de France - ACPR. Our analysis sheds a first light on the role of the loss absorbing capacity and its paramount importance in the Solvency II capital charge computations. We conclude with a number of policy recommendations for insurance regulators.
- Published
- 2017
37. Minimax optimality in robust detection of a disorder time in doubly-stochastic Poisson processes
- Author
-
El Karoui, Nicole, primary, Loisel, Stéphane, additional, and Salhi, Yahia, additional
- Published
- 2017
- Full Text
- View/download PDF
38. On an asymptotic rule A+B/u for ultimate ruin probabilities under dependence by mixing
- Author
-
Dutang, Christophe, Lefèvre, Claude, Loisel, Stéphane, Laboratoire de Sciences Actuarielle et Financière (SAF), Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon, Institut de Recherche Mathématique Avancée (IRMA), Université de Strasbourg (UNISTRA)-Centre National de la Recherche Scientifique (CNRS), Département de Mathématique [Bruxelles] (ULB), Faculté des Sciences [Bruxelles] (ULB), Université libre de Bruxelles (ULB)-Université libre de Bruxelles (ULB), Loisel, Stéphane, and Centre National de la Recherche Scientifique (CNRS)-Université de Strasbourg (UNISTRA)
- Subjects
[MATH.MATH-PR]Mathematics [math]/Probability [math.PR] ,[MATH.MATH-PR] Mathematics [math]/Probability [math.PR] ,[SHS.ECO] Humanities and Social Sciences/Economics and Finance ,[SHS.ECO]Humanities and Social Sciences/Economics and Finance - Abstract
International audience; The purpose of this paper is to point out that an asymptotic rule "A+B/u" for the ultimate ruin probability applies to a wide class of dependent risk models, in discrete and continuous time. Dependence is incorporated through a mixing approach among claim amounts or claim inter-arrival times, leading to a systemic risk behavior. Ruin corresponds here either to classical ruin, or to stopping the activity after realizing that it is not pro table at all, when one has little possibility to increase premium income rate. Several special cases for which closed formulas are derived, are also investigated in some detail.
- Published
- 2013
39. Contribution à la gestion quantitative des risques en assurance
- Author
-
Loisel, Stéphane, Laboratoire de Sciences Actuarielle et Financière (SAF), Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon, Université Claude Bernard - Lyon I, Jean-Paul Laurent, and Loisel, Stéphane
- Subjects
actuariat ,processus stochastiques ,[SHS.GESTION]Humanities and Social Sciences/Business administration ,[MATH] Mathematics [math] ,Probabilités ,[MATH]Mathematics [math] ,[SHS.GESTION] Humanities and Social Sciences/Business administration - Abstract
Ce document pr\ésente une synthèse de mes travaux sur des problématiques de mathématiques appliquées à l'actuariat. La théorie du risque, également appelée théorie de la ruine, concerne d'une manière générale l'évaluation de probabilités de réalisations d'événements défavorables pour des compagnies d'assurances. Au-delà de ces calculs de probabilités dans un modèle fixé, des branches de cette théorie s'intéressent aussi à différents problèmes d'optimisation: d'allocation de réserve, de stratégie de versement de dividendes ou d'imposition (au sens de la fiscalité), d'investissement dans des actifs risqués, de programme de réassurance...
- Published
- 2010
40. Correlation crises in insurance and finance, and the need for dynamic risk maps in ORSA
- Author
-
Loisel, Stéphane, Arnal, Pierre, Durand, Romain, Laboratoire de Sciences Actuarielle et Financière (SAF), Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon, Actuaris, ANR-08-BLAN-0314-01,ANR-08-BLAN-0314-01, Loisel, Stéphane, and - AST&Risk2008 - ANR-08-BLAN-0314 - BLANC - VALID
- Subjects
[SHS.ECO] Humanities and Social Sciences/Economics and Finance ,[SHS.ECO]Humanities and Social Sciences/Economics and Finance - Abstract
We explain why correlation crises may occur in insurance and finance. These phenomena are not taken into account in Solvency II standard formula. We show the importance of taking them into account in internal models or partial internal models. Given the variety of scenarios that could lead to correlation crises and their different potential impacts, we support the idea that ORSA (Own Risk and Solvency Assessment) reports of insurance companies should include dynamic and causal correlation crises analyzes.
- Published
- 2010
41. A trivariate non-Gaussian copula having 2-dimensional Gaussian copulas as margins
- Author
-
Loisel, Stéphane, Loisel, Stéphane, and - AST&Risk2008 - ANR-08-BLAN-0314 - BLANC - VALID
- Subjects
Gaussian copula ,pairwise and global normality ,trivariate copulas with fixed bivariate copulas ,[SHS.ECO] Humanities and Social Sciences/Economics and Finance - Abstract
Arthur Charpentier (see Arthur's blog) was recently contacted by some researchers willing to test if a multivariate copula is - or not - Gaussian. They use a test proposed in Malevergne and Sornette (2003) stating that one should simply test for pairwise normality. This test may be of importance in finance, in actuarial science, and in risk management in general: for example, given 120 financial assets, in order to test whether or not some 120-dimensional random vector of interest in finance admits a Gaussian copula, can one restrict the Gaussian copula hypothesis test to pairs of assets? This short note proves that it is not the case, and provides a simple counter-example based on some multivariate EFGM copula. This confirms the intuition that one cannot only consider all pairs of the studied random variables and that one cannot avoid to study the full vector to test whether a random vector admits a Gaussian copula. An earlier counter-example, discovered after writing this note, is also mentioned.
- Published
- 2009
42. Impact of correlation crises in risk theory
- Author
-
Biard, Romain, Lefèvre, Claude, Loisel, Stéphane, and Loisel, Stéphane
- Subjects
ruin theory ,correlation crisis ,[MATH.MATH-PR] Mathematics [math]/Probability [math.PR] ,non-stationarity ,Sub-prime effect ,heavy-tailed claim size distribution ,asymptotic behavior ,Finite-time ruin probabilities ,processes with dependent increments ,[SHS.ECO] Humanities and Social Sciences/Economics and Finance - Abstract
In the renewal risk model, several strong hypotheses may be found too restrictive to model accurately the complex evolution of the reserves of an insurance company. In the case where claim sizes are heavy-tailed, we relax independence and stationarity assumptions and extend some asymptotic results on finite-time ruin probabilities, to take into account possible correlation crises like the one recently bred by the sub-prime crisis: claim amounts, in general assumed to be independent, may suddenly become strongly positively dependent. The impact of dependence and non-stationarity is analyzed and several concrete examples are given.
- Published
- 2008
43. In the core of longevity risk: hidden dependence in stochastic mortality models and cut-offs in prices of longevity swaps
- Author
-
Loisel, Stéphane, Serant, Daniel, Laboratoire de Sciences Actuarielle et Financière (SAF), Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon, and Loisel, Stéphane
- Subjects
multivariate process ,logit ,longevity swap ,[SHS.ECO] Humanities and Social Sciences/Economics and Finance ,[SHS.ECO]Humanities and Social Sciences/Economics and Finance ,Longevity risk,longevity swap,inter-age correlations,stochastic mortality,multivariate process,logit,Lee-Carter ,stochastic mortality ,Lee-Carter ,Longevity risk ,inter-age correlations - Abstract
In most stochastic mortality models, either one stochastic intensity process (for example a jump-diffusion process) or a collection of independent processes is used to model the stochastic evolution of survival probabilities. We propose and calibrate a new model that takes inter-age correlations into account. The so-called stochastic logit's Deltas model is based on the study of the multivariate time series of the differences of logits of yearly mortality rates. These correlations are important and we illustrate our study on a real-life portfolio. We determine their impact on the price of a longevity swap type reinsurance contract, in which most of the financial risk is taken by a third party. The hypotheses of our model are statistically tested and various measures of risk of the present value of liabilities are found to be significantly smaller in our model than in the case of one common underlying stochastic process.
- Published
- 2007
44. Discrete Schur-constant models
- Author
-
Castañer, Anna, Claramunt, Mercè M.M., Lefèvre, Claude, Loisel, Stéphane, Castañer, Anna, Claramunt, Mercè M.M., Lefèvre, Claude, and Loisel, Stéphane
- Abstract
This paper introduces a class of Schur-constant survival models, of dimension n, for arithmetic non-negative random variables. Such a model is defined through a univariate survival function that is shown to be n-monotone. Two general representations are obtained, by conditioning on the sum of the n variables or through a doubly mixed multinomial distribution. Several other properties including correlation measures are derived. Three processes in insurance theory are discussed for which the claim interarrival periods form a Schur-constant model., SCOPUS: ar.j, info:eu-repo/semantics/published
- Published
- 2015
45. Phase-type aging modeling for health dependent costs
- Author
-
Govorun, Maria, Latouche, Guy, Loisel, Stéphane, Govorun, Maria, Latouche, Guy, and Loisel, Stéphane
- Abstract
In the present paper we develop recursive algorithms to evaluate the distribution of the net present value (abbreviated as "NPV") of a health care contract. The duration of the program is a random variable representing the lifetime of an individual. We suggest a discrete time phase-type approach to model individual health care costs. In this approach, annual health care costs depend naturally on the health state of the individual. We also derive the distribution of the NPV assuming that annual health care costs are iid random variables. We demonstrate analytically that, under special parametrization, the model with iid costs gives a similar expectation of the NPV to the one of the model with health dependent costs. We propose techniques to evaluate the impact of health related events and demonstrate it on numerical examples. Based on Canadian government data on health expenditures, we study the impact on the NPV of the health cost structure by age., SCOPUS: ar.j, info:eu-repo/semantics/published
- Published
- 2015
46. Facteurs explicatifs du rachat en Assurance-Vie : classification et prévisions du risque de rachat
- Author
-
Milhaud, Xavier, Loisel, Stéphane, Maume-Deschamps, Véronique, Laboratoire de Sciences Actuarielle et Financière (SAF), Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon, Axa Cessions, AXA, and Sfds-Hal, Conférence
- Subjects
[STAT.TH] Statistics [stat]/Statistics Theory [stat.TH] ,[MATH.MATH-ST]Mathematics [math]/Statistics [math.ST] ,[STAT.TH]Statistics [stat]/Statistics Theory [stat.TH] ,[MATH.MATH-ST] Mathematics [math]/Statistics [math.ST] - Abstract
International audience; En Assurance Vie, certaines caractéristiques de contrats jouent un rôle majeur dans la décision de l'assuré de racheter son contrat. Les conditions de souscription, son âge, sa profession ainsi que d'autres facteurs propres à sa situation lors de la souscription influencent ses décisions. Il est également possible que l'environnement économique et financier soit important. Deux modèles de segmentation nous ont permis de développer ces idées : les arbres de classification et de régression, et la régression logistique. Les contrats de type Prévoyance ainsi que ceux d'Epargne sont impactés, et les résultats montrent clairement que la garantie de participation au bénéfice est très discriminante. Nous nous focalisons dans cette étude sur des produits de type Mixte. Nous présentons dans un premier temps les fondamentaux de chacun des modèles ainsi que leurs hypothèses et limites. Puis nous testons différents facteurs comme possibles déclencheurs de la décision de rachat, dans le but de segmenter le portefeuille en classe de risque : la duration du contrat et l'option de participation au bénéfice sont des éléments essentiels. En dernière partie, nous discutons des différences entre les deux modélisations en termes de résultats numériques et d'un point de vue opérationnel.
- Published
- 2010
47. Differentiation of some functionals of risk processes.: Applications to ruin theory and to determination of optimal reserve allocation for multidimensional risk processes
- Author
-
Loisel, Stéphane, Laboratoire de Sciences Actuarielle et Financière (SAF), Université Claude Bernard Lyon 1 (UCBL), and Université de Lyon-Université de Lyon
- Subjects
Ruin theory,Sample path properties,Optimal allocation,Multidimensional risk process,Risk measures ,Optimal allocation ,Multidimensional risk process ,Ruin theory ,Sample path properties ,Risk measures ,[SHS.ECO]Humanities and Social Sciences/Economics and Finance - Abstract
International audience; For general risk processes, the expected time-integrated negative part of the process on a fixed time interval is introduced and studied. Differentiation theorems are stated and proved. They make it possible to derive the expected value of this risk measure, and to link it with the average total time below zero studied by Dos Reis (1993) and the probability of ruin. Differentiation of other functionals of unidimensional and multidimensional risk processes with respect to the initial reserve level are carried out. Applications to ruin theory, and to the determination of the optimal allocation of the global initial reserve which minimizes one of these risk measures, illustrate the variety of application fields and the benefits deriving from an efficient and effective use of such tools.
- Published
- 2005
48. A survey of some recent results on Risk Theory
- Author
-
Avram, Florin, primary, Biard, Romain, additional, Dutang, Christophe, additional, Loisel, Stéphane, additional, and Rabehasaina, Landy, additional
- Published
- 2014
- Full Text
- View/download PDF
49. On an asymptotic rule A + B / u for ultimate ruin probabilities under dependence by mixing
- Author
-
Dutang, Christophe, Lefèvre, Claude, Loisel, Stéphane, Dutang, Christophe, Lefèvre, Claude, and Loisel, Stéphane
- Abstract
The purpose of this paper is to point out that an asymptotic rule A + B / u for the ultimate ruin probability applies to a wide class of dependent risk processes, in continuous or discrete time. That dependence is incorporated through a mixing model in the individual claim amount distributions. Several special mixing distributions are examined in detail and some close-form formulas are derived. Claim tail distributions and the dependence structure are also investigated. © 2013., SCOPUS: ar.j, info:eu-repo/semantics/published
- Published
- 2013
50. Impact of Climate Change on Heat Wave Risk
- Author
-
Biard, Romain, primary, Blanchet-Scalliet, Christophette, additional, Eyraud-Loisel, Anne, additional, and Loisel, Stéphane, additional
- Published
- 2013
- Full Text
- View/download PDF
Catalog
Discovery Service for Jio Institute Digital Library
For full access to our library's resources, please sign in.