Method of Winsorized Moments for Robust Fitting of Truncated and Censored Lognormal Distributions

Fuente: arXiv
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Autori principali: Poudyal, Chudamani, Zhao, Qian, Brazauskas, Vytaras
Natura: Preprint
Pubblicazione: 2022
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author Poudyal, Chudamani
Zhao, Qian
Brazauskas, Vytaras
author_facet Poudyal, Chudamani
Zhao, Qian
Brazauskas, Vytaras
contents When constructing parametric models to predict the cost of future claims, several important details have to be taken into account: (i) models should be designed to accommodate deductibles, policy limits, and coinsurance factors, (ii) parameters should be estimated robustly to control the influence of outliers on model predictions, and (iii) all point predictions should be augmented with estimates of their uncertainty. The methodology proposed in this paper provides a framework for addressing all these aspects simultaneously. Using payment-per-payment and payment-per-loss variables, we construct the adaptive version of method of winsorized moments (MWM) estimators for the parameters of truncated and censored lognormal distribution. Further, the asymptotic distributional properties of this approach are derived and compared with those of the maximum likelihood estimator (MLE) and method of trimmed moments (MTM) estimators. The latter being a primary competitor to MWM. Moreover, the theoretical results are validated with extensive simulation studies and risk measure sensitivity analysis. Finally, practical performance of these methods is illustrated using the well-studied data set of 1500 U.S. indemnity losses. With this real data set, it is also demonstrated that the composite models do not provide much improvement in the quality of predictive models compared to a stand-alone fitted distribution specially for truncated and censored sample data.
format Preprint
id arxiv_https___arxiv_org_abs_2204_02477
institution arXiv
publishDate 2022
record_format arxiv
spellingShingle Method of Winsorized Moments for Robust Fitting of Truncated and Censored Lognormal Distributions
Poudyal, Chudamani
Zhao, Qian
Brazauskas, Vytaras
Methodology
When constructing parametric models to predict the cost of future claims, several important details have to be taken into account: (i) models should be designed to accommodate deductibles, policy limits, and coinsurance factors, (ii) parameters should be estimated robustly to control the influence of outliers on model predictions, and (iii) all point predictions should be augmented with estimates of their uncertainty. The methodology proposed in this paper provides a framework for addressing all these aspects simultaneously. Using payment-per-payment and payment-per-loss variables, we construct the adaptive version of method of winsorized moments (MWM) estimators for the parameters of truncated and censored lognormal distribution. Further, the asymptotic distributional properties of this approach are derived and compared with those of the maximum likelihood estimator (MLE) and method of trimmed moments (MTM) estimators. The latter being a primary competitor to MWM. Moreover, the theoretical results are validated with extensive simulation studies and risk measure sensitivity analysis. Finally, practical performance of these methods is illustrated using the well-studied data set of 1500 U.S. indemnity losses. With this real data set, it is also demonstrated that the composite models do not provide much improvement in the quality of predictive models compared to a stand-alone fitted distribution specially for truncated and censored sample data.
title Method of Winsorized Moments for Robust Fitting of Truncated and Censored Lognormal Distributions
topic Methodology
url https://arxiv.org/abs/2204.02477