PLAYGROUND

ECUACIONES DISTRIBUCIÓN F NO CENTRAL

Definición de distribución

XNonCentralF(λ,n1,n2)X\sim\mathrm{NonCentralF}\left(\lambda,n_{1},n_{2}\right)

Dominio de distribución

x[0,)x\in [0,\infty)

Dominio y restricciones de parámetros

λR+,n1R+,n2R+\lambda\in\mathbb{R}^{+},n_{1}\in\mathbb{R}^{+},n_{2}\in\mathbb{R}^{+}

Función de distribución acumulada

FX(x)=j=0((12λ)jj!eλ/2)In1x/(n2+n1x)(n12+j,n22)F_{X}\left(x\right)=\sum\limits_{j=0}^\infty\left(\frac{\left(\frac{1}{2}\lambda\right)^j}{j!}e^{-\lambda/2}\right)I_{n_1x/(n_2+n_1x)}\left(\frac{n_1}{2}+j,\frac{n_2}{2}\right)

Función de densidad de probabilidad

fX(x)=k=0eλ/2(λ/2)kBeta(n22,n12+k)k!(n1n2)n12+k(n2n2+n1x)n1+n22+kxn1/21+kf_{X}\left(x\right)=\sum\limits_{k=0}^\infty\frac{e^{-\lambda/2}(\lambda/2)^k}{ \text{Beta}\left(\frac{n_2}{2},\frac{n_1}{2}+k\right) k!}\left(\frac{n_1}{n_2}\right)^{\frac{n_1}{2}+k}\left(\frac{n_2}{n_2+n_1x}\right)^{\frac{n_1+n_2}{2}+k}x^{n_1/2-1+k}

Función de punto percentil

SampleX=(i=1n1(λn1+Φ1(ui))2)/n1(2P1(n22,u))/n2\text{Sample}_{X}=\frac{\left(\sum_{i=1}^{n_1}\left(\sqrt{\frac{\lambda}{n_1}}+\Phi^{-1}\left(u_{i}\right)\right)^{2}\right)/n_1}{\left(2\text{P}^{-1}\left(\frac{n_2}{2},u\right)\right)/n_2}

Momentos paramétricos no centrados

μk=E[Xk]=0xkfX(x)dx=eλ/2(n1n2)kΓ(n1/2k)Γ(n1/2)r=0(1r!)(λ2)rΓ(n12+r+k)Γ(n12+r)\mu'_{k}=E[X^k]=\int_{0}^{\infty}x^{k}f_{X}\left(x\right)dx=e^{-\lambda/2}\left(\frac{n1}{n2}\right)^{k}\frac{\Gamma\left(n_1/2-k\right)}{\Gamma\left(n_1/2\right)}\sum_{r=0}^{\infty }\left(\frac{1}{r!}\right)\left(\frac{\lambda}{2}\right)^{r}\frac{\Gamma\left(\frac{n_1}{2}+r+k\right)}{\Gamma\left(\frac{n_1}{2}+r\right)}

Media paramétrica

Mean(X)=μ1\mathrm{Mean}(X)=\mu'_{1}

Varianza paramétrica

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

Coeficiente de asimetría paramétrico

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

Curtosis paramétrica

Kurtosis(X)=μ44μ1μ3+6μ12μ23μ14(μ2μ12)2\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}}

Mediana paramétrica

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

Moda paramétrica

Mode(X)=argmaxxfX(x)\mathrm{Mode}(X)=\arg\max_{x}f_{X}\left(x\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.}
u:Uniform[0,1] random varibleu:\text{Uniform[0,1] random varible}
ui:Uniform[0,1] random varibleu_{i}:\text{Uniform[0,1] random varible}
Φ1(x):PPF normal standard distribution\Phi^{-1}\left(x\right):\text{PPF normal standard distribution}
P1(a,u):Inverse of regularized lower incomplete gamma function\text{P}^{-1}\left(a,u\right):\text{Inverse of regularized lower incomplete gamma function}
I(x,a,b):Regularized incomplete beta functionI\left(x,a,b\right):\text{Regularized incomplete beta function}
Beta(x,y):Beta function\text{Beta}\left(x,y\right):\text{Beta function}