Bounds of the Normal Approximation for Linear Recursions with Two Effects

Authors

  • Mongkhon Tuntapthai

Keywords:

Hierarchical sequence, Stein's method, Zero bias

Abstract

Let gif.latex?X_0 be a non-constant random variable with finite variance. Given an integer gif.latex?k\geq&space;2, define a sequence gif.latex?\{X_n\}^{\infty}_{n=1} of approximately linear recursions with small perturbations gif.latex?\{\Delta_n\}^{\infty}_{n=0} by

gif.latex?X_{n+1}=\sum_{i=1}^{k}a_{n,i}X_{n,i}+\Delta_{n}&space;\text{&space;for&space;all&space;}&space;n&space;\geq&space;0

where gif.latex?X_{n,1},\ldots,X_{n,k} are independent copies of the gif.latex?X_{n} and gif.latex?a_{n,1},\ldots,a_{n,k} are real numbers. In 2004, Goldstein obtained bounds on the Wasserstein distance between the standard normal distribution and the law of gif.latex?X_{n} which is in the form gif.latex?C&space;\gamma^{n} for some constants gif.latex?C > gif.latex?0 and gif.latex?0 <  gif.latex?\gamma < gif.latex?1.

In this article, we extend the results to the case of two effects by studying a linear model gif.latex?Z_{n}=X_{n}+Y_{n} for all gif.latex?n\geq0, where gif.latex?\{Y_n\}^{\infty}_{n=1} is a sequence of approximately linear recursions with an initial random variable gif.latex?Y_{0} and perturbations gif.latex?\{\Lambda_n\}^{\infty}_{n=0}, i.e., for some gif.latex?\ell\geq2,

gif.latex?Y_{n+1}=\sum_{j=1}^{\ell}b_{n,j}Y_{n,j}+\Lambda_{n}&space;\text{&space;for&space;all&space;}&space;n&space;\geq&space;0

where gif.latex?Y_{n} and gif.latex?Y_{n,1},\ldots,Y_{n,\ell} are independent and identically distributed random variables and gif.latex?b_{n,1},\ldots,b_{n,\ell} are real numbers. Applying the zero bias transformation in the Stein's equation, we also obtain the bound for gif.latex?Z_{n}. Adding further conditions that the two models gif.latex?(X_{n},\Delta_{n}) and gif.latex?(Y_{n},\Lambda_{n}) are independent and that the difference between variance of gif.latex?X_{n} and gif.latex?Y_{n} is smaller than the sum of variances of their perturbation parts, our result is the same as previous work.

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Published

2019-12-21

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Section

Research Articles