[R] sample size/power calc packages

[Peter Dalgaard]

rossini at blindglobe.net (A.J. Rossini) writes:

> For various reasons, I spent part of my time today looking at sample
> size and power calculation tools (don't ask, don't tell...).  This
> seems to be one area that R is incredibly weak in (well, nearly all
> stat packages, except perhaps specialized tools and SAS); sure, there
> are a number of functions in various packages:
> 
>           base, statmod, Hmisc
> 
> Have I missed something?  (I would've expected at least one sequential
> computation, or non-standard design, but apparently there are none, or
> I missed it).  
> 
> I'd appreciate hearing about work that I've missed...

Is SAS particularly hot? I've just been explaining to people how to
cheat SAS Analyst into letting the Two-Sample t-Test sample-sizer do
binomial proportions with a fudged SD.

I think Claus Ekstrøm submitted a modification power.t.test for
unequal sample size, but he wasn't sufficiently assertive that it was
actually done right, so it didn't get in.

One thing we really ought to get around to soon is sample sizing for
equivalence studies. And, yes, sequential procedures would be obvious
too.

-- 
   O__  ---- Peter Dalgaard             Blegdamsvej 3  
  c/ /'_ --- Dept. of Biostatistics     2200 Cph. N   
 (*) \(*) -- University of Copenhagen   Denmark      Ph: (+45) 35327918
~~~~~~~~~~ - (p.dalgaard at biostat.ku.dk)             FAX: (+45) 35327907