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Distribution

If XโˆผN(0,1)X \sim N(0,1), then Z=X2โˆผX2(1)\mathbb{Z} = X^2 \sim \mathcal{X}^2(1)

Beta(ฮฑ\alpha, ฮฒ\beta) 0<x<10 < x < 1

Uniform (ฮฑ\alpha, ฮฒ\beta) a<x<ba < x < b

Gamma ฮณ(ฮฑ,ฮฒ)\gamma(\alpha, \beta)

f(x)=xฮฑโˆ’1ฮ“(ฮฑ)ฮธฮฑeโˆ’xฮธf(x) = {x^{\alpha - 1} \over \Gamma(\alpha) \theta^\alpha} e^{-x \over \theta}

Exponential(ฮธ\theta) = ฮณ(ฮฑ=1,theta)\gamma(\alpha = 1, theta)

Chi-squared(ฮณ\gamma) = ฮณ(ฮฑ=ฮณ2,ฮธ=2)\gamma(\alpha = {\gamma \over 2}, \theta = 2)

XโˆผN(ฮผ,ฯƒx2)\mathcal{X} \sim N(\mu, \sigma_x^2) โ†’ 12ฯ€ฯƒeโˆ’(xโˆ’ฮผ)22ฯƒx2{1 \over \sqrt{2 \pi} \sigma} e^{-{(x-\mu)^2} \over {2\sigma_x^2}}

Y=g(x)Y=g(x)

fy(y)=โˆ‘xkfx(xk)โˆฃdxdyโˆฃ@x=xkf_y(y) = \sum\limits_{x_k} f_x(x_k) |{dx \over dy}|_{\text{@} x = x_k}