[R] (no subject)

Ben Bolker bolker at ufl.edu
Fri Aug 17 17:30:30 CEST 2007

mara serrano <teachermara <at> yahoo.com> writes:

> hi,
> i'm new to R and i'm trying to port a quattro pro spreadsheet into R.
spreadsheets have optional lower and
> upper limit parameters on the beta distribution function. i would like to know
how to incorporate this
> with R's pbeta function.
> thanks in advance,
> mara.

  I think (?) you may mean a beta distribution with
limits scaled other than the standard 0 and 1.
You will have to construct these yourself but it's
fairly easy to do, e.g.

dbeta.scaled <- function(x,shape1,shape2,min,max,...) {
   x.scaled <- (x-min)/(max-min)

and similarly for pbeta.

For rbeta (and qbeta) the scaling has to go in the other direction.

rbeta.scaled <- function(n,shape1,shape2,min,max,...) {

  I did something like this for Tiwari et al. (2006)
Marine Ecology Progress Series 326:283-293 (although the
paper doesn't include any R code).

    Ben Bolker

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