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In probability theory, an empirical process is a stochastic process that describes the proportion of objects in a system in a given state. For a process in a discrete state space a population continuous time Markov chain or Markov population model is a process which counts the number of objects in a given state (without rescaling). In mean field theory, limit theorems (as the number of objects becomes large) are considered and generalise the central limit theorem for empirical measures. Applications of the theory of empirical processes arise in non-parametric statistics. ==Definition== For ''X''1, ''X''2, ... ''X''''n'' independent and identically-distributed random variables in R with common cumulative distribution function ''F''(''x''), the empirical distribution function is defined by : where I''C'' is the indicator function of the set ''C''. For every (fixed) ''x'', ''F''''n''(''x'') is a sequence of random variables which converge to ''F''(''x'') almost surely by the strong law of large numbers. That is, ''F''''n'' converges to ''F'' pointwise. Glivenko and Cantelli strengthened this result by proving uniform convergence of ''F''''n'' to ''F'' by the Glivenko–Cantelli theorem. A centered and scaled version of the empirical measure is the signed measure : It induces a map on measurable functions ''f'' given by : By the central limit theorem, converges in distribution to a normal random variable ''N''(0, ''P''(''A'')(1 − ''P''(''A''))) for fixed measurable set ''A''. Similarly, for a fixed function ''f'', converges in distribution to a normal random variable , provided that and exist. Definition :, a collection of measurable subsets of ''S''. :, a collection of measurable functions from ''S'' to . A significant result in the area of empirical processes is Donsker's theorem. It has led to a study of Donsker classes: sets of functions with the useful property that empirical processes indexed by these classes converge weakly to a certain Gaussian process. While it can be shown that Donsker classes are Glivenko–Cantelli classes, the converse is not true in general. 抄文引用元・出典: フリー百科事典『 ウィキペディア(Wikipedia)』 ■ウィキペディアで「empirical process」の詳細全文を読む スポンサード リンク
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