|
\right)-\frac | variance =| skewness =| kurtosis =| entropy =| mgf = | cf = | }} In probability theory, an exponentially modified Gaussian (EMG) distribution (ExGaussian distribution) describes the sum of independent normal and exponential random variables. An exGaussian random variable Z may be expressed as Z = ''X'' + ''Y'' where ''X'' and ''Y'' are independent, ''X'' is Gaussian with mean ''μ'' and variance ''σ''2 and ''Y'' is exponential of rate ''λ''. It has a characteristic positive skew from the exponential component. It may also be regarded as a weighted function of a shifted exponential with the weight being a function of the normal distribution. ==Definition== The probability density function (pdf) of the exponentially modified normal distribution is : where erfc is the complementary error function defined as : This density function is derived via convolution of the normal and exponential probability density functions. The density function is a solution of the following differential equation: : 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「Exponentially modified Gaussian distribution」の詳細全文を読む スポンサード リンク
|