- Berry–Esséen theorem
The
central limit theorem inprobability theory andstatistics states that under certain circumstances thesample mean , considered as arandom quantity, becomes more normally distributed as the sample size is increased. The Berry–Esseen theorem, also known as the Berry–Esseen inequality, attempts to quantify the "rate" at which thisconvergence to normality takes place.Statements of the theorem vary, as it was independently discovered by two
mathematician s,Andrew C. Berry (in1941 ) andCarl-Gustav Esseen (1942 ), who then, along with other authors, refined it repeatedly over subsequent decades.One version, sacrificing generality somewhat for the sake of clarity, is the following:
:Let "X"1, "X"2, ..., be i.i.d. random variables with E("X"1) = 0, E("X"12) = σ2 > 0, and E(|"X"1|3) = ρ < . Also, let:::be the sample mean, with "F""n" the cdf of:::and Φ the cdf of the
standard normal distribution . Then there exists a positiveconstant "C" such that for all "x" and "n",::That is: given a sequence of
Independent identically-distributed random variables , each havingmean zero and positivevariance , if additionally the third absolute moment is finite, then thecumulative distribution function s of the standardizedsample mean and thestandard normal distribution differ (vertically, on a graph) by no more than the specified amount. Note that the rate of convergence is on the order of "n"−1/2.Calculated values of the constant "C" have decreased markedly over the years, from 7.59 (Esseen's original bound) to 0.7975 in
1972 (byP. van Beeck ). The best current bound is 0.7655 (byI. S. Shiganov in1986 ).ee also
*
Chernoff's inequality
*Inequality
*List of inequalities
*List of mathematical theorems External links
* Chen, Po-Ning (2002). [http://shannon.cm.nctu.edu.tw/html/paper/be02.pdf Asymptotic Refinement of the Berry-Esseen Constant] . A PDF file retrieved Mar. 9, 2004.
* Gut, Allan & Holst Lars. [http://www.stat.unipd.it/bernoulli/02a/bn_3.html Carl-Gustav Esseen] , retrieved Mar. 15, 2004.References
* Durrett, Richard (1991). "Probability: Theory and Examples". Pacific Grove, CA: Wadsworth & Brooks/Cole. ISBN 0-534-13206-5.
* Feller, William (1972). "An Introduction to Probability Theory and Its Applications, Volume II" (2nd ed.). New York: John Wiley & Sons. ISBN 0-471-25709-5.
* Manoukian, Edward B. (1986). "Modern Concepts and Theorems of Mathematical Statistics". New York: Springer-Verlag. ISBN 0-387-96186-0.
* Serfling, Robert J. (1980). "Approximation Theorems of Mathematical Statistics". New York: John Wiley & Sons. ISBN 0-471-02403-1.
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