[R] Tail area of sum of Chi-square variables

[Thomas Lumley]

On Thu, 29 Mar 2007, Klaus Nordhausen wrote:
>
> I was wondering if there are any R functions that give the tail area
> of a sum of chisquare distributions of the type:
>         a_1 X_1 + a_2 X_2
> where a_1 and a_2 are constants and X_1 and X_2 are independent chi-square variables with different degrees of freedom.
>

pchisqsum() in the "survey" package does this.

 	-thomas

Thomas Lumley			Assoc. Professor, Biostatistics
tlumley at u.washington.edu	University of Washington, Seattle