On the approximation of sum of lognormal for correlated variates and implementation.

In probabilistic modeling across engineering, finance, and telecommunications, sums of lognormal random variables frequently occur, yet no closed-form expression exists for their distribution. This study systematically evaluates three approximation methods-Wilkinson (W), Schwartz & Yeh (SY), and...

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Main Authors: Asyraf Nadia Mohd Yunus, Nora Muda, Abdul Rahman Othman, Sonia Aïssa
Format: Article
Language:English
Published: Public Library of Science (PLoS) 2025-01-01
Series:PLoS ONE
Online Access:https://doi.org/10.1371/journal.pone.0325647
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author Asyraf Nadia Mohd Yunus
Nora Muda
Abdul Rahman Othman
Sonia Aïssa
author_facet Asyraf Nadia Mohd Yunus
Nora Muda
Abdul Rahman Othman
Sonia Aïssa
author_sort Asyraf Nadia Mohd Yunus
collection DOAJ
description In probabilistic modeling across engineering, finance, and telecommunications, sums of lognormal random variables frequently occur, yet no closed-form expression exists for their distribution. This study systematically evaluates three approximation methods-Wilkinson (W), Schwartz & Yeh (SY), and Inverse (I)-for correlated lognormal variates across varying sample sizes and correlation structures. Using Monte Carlo simulations with 5, 15, 25, and 30 samples and correlation coefficients of 0.3, 0.6, and 0.9, we compared Type I error rates through Anderson-Darling goodness-of-fit tests. Our findings demonstrate that the Wilkinson approximation consistently outperforms the other methods for correlated variates, exhibiting the lowest Type I error rates across all tested scenarios. This contradicts some previous findings in telecommunications literature where SY was preferred. We validated these results using real-world datasets from engineering (fatigue life of ball bearings) and finance (stock price correlations), confirming the Wilkinson approximation's superior performance through probability density function comparisons. This research provides practical guidance for selecting appropriate approximation methods when modeling correlated lognormal sums in diverse applications.
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spelling doaj-art-e0cc908c1ec048589f826d194b0f748b2025-08-20T03:24:07ZengPublic Library of Science (PLoS)PLoS ONE1932-62032025-01-01206e032564710.1371/journal.pone.0325647On the approximation of sum of lognormal for correlated variates and implementation.Asyraf Nadia Mohd YunusNora MudaAbdul Rahman OthmanSonia AïssaIn probabilistic modeling across engineering, finance, and telecommunications, sums of lognormal random variables frequently occur, yet no closed-form expression exists for their distribution. This study systematically evaluates three approximation methods-Wilkinson (W), Schwartz & Yeh (SY), and Inverse (I)-for correlated lognormal variates across varying sample sizes and correlation structures. Using Monte Carlo simulations with 5, 15, 25, and 30 samples and correlation coefficients of 0.3, 0.6, and 0.9, we compared Type I error rates through Anderson-Darling goodness-of-fit tests. Our findings demonstrate that the Wilkinson approximation consistently outperforms the other methods for correlated variates, exhibiting the lowest Type I error rates across all tested scenarios. This contradicts some previous findings in telecommunications literature where SY was preferred. We validated these results using real-world datasets from engineering (fatigue life of ball bearings) and finance (stock price correlations), confirming the Wilkinson approximation's superior performance through probability density function comparisons. This research provides practical guidance for selecting appropriate approximation methods when modeling correlated lognormal sums in diverse applications.https://doi.org/10.1371/journal.pone.0325647
spellingShingle Asyraf Nadia Mohd Yunus
Nora Muda
Abdul Rahman Othman
Sonia Aïssa
On the approximation of sum of lognormal for correlated variates and implementation.
PLoS ONE
title On the approximation of sum of lognormal for correlated variates and implementation.
title_full On the approximation of sum of lognormal for correlated variates and implementation.
title_fullStr On the approximation of sum of lognormal for correlated variates and implementation.
title_full_unstemmed On the approximation of sum of lognormal for correlated variates and implementation.
title_short On the approximation of sum of lognormal for correlated variates and implementation.
title_sort on the approximation of sum of lognormal for correlated variates and implementation
url https://doi.org/10.1371/journal.pone.0325647
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