R help - Aug 2007 - (no subject)

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.




     
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Hi

you do not give much information, even subject line is missing. Try to 
follow posting guide and try to explain what you did and how did you fail.

Regards
 
Petr

r-help-bounces at stat.math.ethz.ch napsal dne 16.08.2007 17:24:24:
> 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.
> 
> 
> 
> 
> 
> 
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> Park yourself in front of a world of choices in alternative vehicles. 
Visit
> 
>    [[alternative HTML version deleted]]
> 
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> PLEASE do read the posting guide 
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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)
   dbeta(x.scaled,shape1,shape2,...)
}

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,...) {
  min+(max-min)*rbeta(n,shape1,shape2,...)
}

  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).

  cheers
    Ben Bolker