Beta Distribution#

There are two shape parameters a,b>0 and the support is x[0,1].

f(x;a,b)=Γ(a+b)Γ(a)Γ(b)xa1(1x)b1F(x;a,b)=x0f(y;a,b)dy=I(x;a,b)G(q;a,b)=I1(q;a,b)M(t)=Γ(a)Γ(b)Γ(a+b)1F1(a;a+b;t)μ=aa+bμ2=ab(a+b+1)(a+b)2γ1=2baa+b+2a+b+1abγ2=6(a3+a2(12b)+b2(b+1)2ab(b+2))ab(a+b+2)(a+b+3)md=(a1)(a+b2)a+b2

where I(x;a,b) is the regularized incomplete Beta function. f(x;a,1) is also called the Power-function distribution.

lx(a,b)=NlogΓ(a+b)+NlogΓ(a)+NlogΓ(b)N(a1)¯logxN(b1)¯log(1x)

Implementation: scipy.stats.beta