PLAYGROUND

ECUACIONES DISTRIBUCIÓN GAUSSIANA INVERSA

Definición de distribución

XInverseGaussian(μ,λ)X\sim\mathrm{InverseGaussian}\left(\mu,\lambda\right)

Dominio de distribución

x(0,)x\in\left(0,\infty\right)

Dominio y restricciones de parámetros

μR+,λR+\mu\in\mathbb{R}^{+},\lambda\in\mathbb{R}^{+}

Función de distribución acumulada

FX(x)=Φ(λx(xμ1))+exp(2λμ)Φ(λx(xμ+1))F_{X}\left(x\right)=\Phi\left(\sqrt{\frac{\lambda}{x}}\left(\frac{x}{\mu}-1\right)\right)+\exp\left(\frac{2 \lambda}{\mu}\right) \Phi\left(-\sqrt{\frac{\lambda}{x}}\left(\frac{x}{\mu}+1\right)\right)

Función de densidad de probabilidad

fX(x)=λ2πx3exp[λ(xμ)22μ2x]f_{X}\left(x\right)=\sqrt\frac{\lambda}{2 \pi x^3} \exp\left[-\frac{\lambda (x-\mu)^2}{2 \mu^2 x}\right]

Función de punto percentil

SampleX={x0if u2μμ+x0μ2x0if u2μμ+x0\text{Sample}_{X}=\left\{\begin{array}{cl} x_{0} \quad \text{if } u_{2}\leqslant\frac{\mu}{\mu+x_{0}}\\ \frac{\mu^{2}}{x_{0}} \quad \text{if } u_{2}\geqslant \frac{\mu}{\mu+x_{0}} \end{array} \right.

Momentos paramétricos no centrados

μk=E[Xk]=0xkfX(x)dx\mu'_{k}=E[X^k]=\int_{0}^{\infty }x^{k}f_{X}\left(x\right)dx

Media paramétrica

Mean(X)=μ1=μ\mathrm{Mean}(X)=\mu'_{1}=\mu

Varianza paramétrica

Variance(X)=μ2μ12=μ3λ\mathrm{Variance}(X)=\mu'_{2}-\mu'^{2}_{1}=\frac{\mu^3}{\lambda}

Coeficiente de asimetría paramétrico

Skewness(X)=μ33μ2μ1+2μ13(μ2μ12)1.5=3(μλ)1/2\mathrm{Skewness}(X)=\frac{\mu'_{3}-3\mu'_{2}\mu'_{1}+2\mu'^{3}_{1}}{(\mu'_{2}-\mu'^{2}_{1})^{1.5}}=3\left(\frac{\mu}{\lambda}\right)^{1/2}

Curtosis paramétrica

Kurtosis(X)=μ44μ1μ3+6μ12μ23μ14(μ2μ12)2=3+15μλ\mathrm{Kurtosis}(X)=\frac{\mu'_{4}-4\mu'_{1}\mu'_{3}+6\mu'^{2}_{1}\mu'_{2}-3\mu'^{4}_{1}}{(\mu'_{2}-\mu'^{2}_{1})^{2}}=3+\frac{15 \mu}{\lambda}

Mediana paramétrica

Median(X)=FX1(12)\mathrm{Median}(X)=F^{-1}_{X}\left(\frac{1}{2}\right)

Moda paramétrica

Mode(X)=μ[(1+9μ24λ2)123μ2λ]\mathrm{Mode}(X)=\mu\left[\left(1+\frac{9 \mu^2}{4 \lambda^2}\right)^\frac{1}{2}-\frac{3 \mu}{2 \lambda}\right]

Información y definiciones adicionales

Computing an analytic expression for the inverse of the cumulative distribution function is notfeasible. Nonetheless, it is possible to generate a random sample from the distribution.\text{Computing an analytic expression for the inverse of the cumulative distribution function is not} \\ \text{feasible. Nonetheless, it is possible to generate a random sample from the distribution.}
Φ(x):CDF normal standard distribution\Phi\left(x\right):\text{CDF normal standard distribution}
Φ1(x):PPF normal standard distribution\Phi^{-1}\left(x\right):\text{PPF normal standard distribution}
x0=μ+μ2[Φ1(u1)]22λμ2λ4μλ[Φ1(u1)]2+μ2([Φ1(u1)]2)2x_{0}=\mu+\frac{\mu^2 [\Phi^{-1}\left(u_{1}\right)]^{2}}{2\lambda}-\frac{\mu}{2\lambda}\sqrt{4\mu \lambda [\Phi^{-1}\left(u_{1}\right)]^{2}+\mu^2 ([\Phi^{-1}\left(u_{1}\right)]^{2})^2}
u1:Uniform[0,1] random varibleu_{1}:\text{Uniform[0,1] random varible}
u2:Uniform[0,1] random varibleu_{2}:\text{Uniform[0,1] random varible}