Stein's method for models with general clocks: A tutorial

Fuente: arXiv
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Main Authors: Braverman, Anton, Scully, Ziv
Format: Preprint
Published: 2025
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author Braverman, Anton
Scully, Ziv
author_facet Braverman, Anton
Scully, Ziv
contents Diffusion approximations are widely used in the analysis of service systems, providing tractable insights into complex models. While heavy-traffic limit theorems justify these approximations asymptotically, they do not quantify the error when the system is not in the limit regime. This paper presents a tutorial on the generator comparison approach of Stein's method for analyzing diffusion approximations in Markovian models where state transitions are governed by general clocks, which extends the well-established theory for continuous-time Markov chains and enables non-asymptotic error bounds for these approximations. Building on recent work that applies this method to single-clock systems, we develop a framework for handling models with multiple general clocks. Our approach is illustrated through canonical queueing systems, including the G/G/1 queue, the join-the-shortest-queue system, and the tandem queue. We highlight the role of the Palm inversion formula and the compensated queue-length process in extracting the diffusion generator. Most of our error terms depend only on the first three moments of the general clock distribution. The rest require deeper, model-specific, insight to bound, but could in theory also depend on only the first three moments.
format Preprint
id arxiv_https___arxiv_org_abs_2503_12189
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Stein's method for models with general clocks: A tutorial
Braverman, Anton
Scully, Ziv
Probability
Primary 60J25, 60F99, secondary 60K25, 60J60
Diffusion approximations are widely used in the analysis of service systems, providing tractable insights into complex models. While heavy-traffic limit theorems justify these approximations asymptotically, they do not quantify the error when the system is not in the limit regime. This paper presents a tutorial on the generator comparison approach of Stein's method for analyzing diffusion approximations in Markovian models where state transitions are governed by general clocks, which extends the well-established theory for continuous-time Markov chains and enables non-asymptotic error bounds for these approximations. Building on recent work that applies this method to single-clock systems, we develop a framework for handling models with multiple general clocks. Our approach is illustrated through canonical queueing systems, including the G/G/1 queue, the join-the-shortest-queue system, and the tandem queue. We highlight the role of the Palm inversion formula and the compensated queue-length process in extracting the diffusion generator. Most of our error terms depend only on the first three moments of the general clock distribution. The rest require deeper, model-specific, insight to bound, but could in theory also depend on only the first three moments.
title Stein's method for models with general clocks: A tutorial
topic Probability
Primary 60J25, 60F99, secondary 60K25, 60J60
url https://arxiv.org/abs/2503.12189