Stochastic Ordering for Bernoulli and Normal Random Walks

Fuente: arXiv
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Autori principali: Hsiau, Shoou-Ren, Yao, Yi-Ching
Natura: Preprint
Pubblicazione: 2025
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author Hsiau, Shoou-Ren
Yao, Yi-Ching
author_facet Hsiau, Shoou-Ren
Yao, Yi-Ching
contents Let $(S_n^p)_{n\geq 0}$ be a Bernoulli random walk where each of the independent increments is either $1$ or $-1$ with probabilities $p$ and $1-p$. For $p'$ and $p'' \in [0,1]$ with $|p'-1/2|>|p''-1/2|$, we show that $(|S_n^{p''}|)_{n\geq 0}$ is stochastically smaller than $(|S_n^{p'}|)_{n\geq 0}$. In other words, $(|S_n^{p}|)_{n\geq 0}$ is stochastically decreasing in $p \in [0,1/2]$ and increasing in $p\in [1/2,1]$. An analogous result is also given for the family of normal random walks indexed by $μ\in R$ where each of the independent increments is normally distributed with common mean $μ$ and variance $1$. Extension to Brownian motion then follows by a limiting argument. As an application, these results are used to easily derive stochastic ordering properties for stopping times of Bernoulli and normal random walks.
format Preprint
id arxiv_https___arxiv_org_abs_2511_14200
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Stochastic Ordering for Bernoulli and Normal Random Walks
Hsiau, Shoou-Ren
Yao, Yi-Ching
Probability
Let $(S_n^p)_{n\geq 0}$ be a Bernoulli random walk where each of the independent increments is either $1$ or $-1$ with probabilities $p$ and $1-p$. For $p'$ and $p'' \in [0,1]$ with $|p'-1/2|>|p''-1/2|$, we show that $(|S_n^{p''}|)_{n\geq 0}$ is stochastically smaller than $(|S_n^{p'}|)_{n\geq 0}$. In other words, $(|S_n^{p}|)_{n\geq 0}$ is stochastically decreasing in $p \in [0,1/2]$ and increasing in $p\in [1/2,1]$. An analogous result is also given for the family of normal random walks indexed by $μ\in R$ where each of the independent increments is normally distributed with common mean $μ$ and variance $1$. Extension to Brownian motion then follows by a limiting argument. As an application, these results are used to easily derive stochastic ordering properties for stopping times of Bernoulli and normal random walks.
title Stochastic Ordering for Bernoulli and Normal Random Walks
topic Probability
url https://arxiv.org/abs/2511.14200