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A gamma process is a random process with independent gamma distributed increments. Often written as , it is a pure-jump increasing Lévy process with intensity measure , for positive . Thus jumps whose size lies in the interval occur as a Poisson process with intensity The parameter controls the rate of jump arrivals and the scaling parameter inversely controls the jump size. It is assumed that the process starts from a value 0 at ''t''=0. The gamma process is sometimes also parameterised in terms of the mean () and variance () of the increase per unit time, which is equivalent to and . ==Properties== Some basic properties of the gamma process are: ;marginal distribution The marginal distribution of a gamma process at time , is a gamma distribution with mean and variance ;scaling : ;adding independent processes : ;moments : where is the Gamma function. ;moment generating function : ;correlation : 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「Gamma process」の詳細全文を読む スポンサード リンク
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