R help - Apr 2009 - problem about finding power in test about variances

Hello All

I am new to this list. I have a problem where for a single sample drawn from
normal population, null hypothesis is that variance = k (say). Alternative
hypothesis is variance > k. Now if we know the true variance, then I would
like to calculate the sample size required to produce certain power (for some
significance). How do I do this ? I thought of using pwr.chisq.test, and I
contacted the author stephane champely, but he said his package can't do
this. Does anybody have an idea ?

Thanks
Ati

ati sundar wrote:
> Hello All
> 
> I am new to this list. I have a problem where for a single sample drawn
from normal population, null hypothesis is that variance = k (say).
Perhaps you want to tell us more precisely what you are going to do 
rather than asking the same inprecise question again and again 
(including messages to single persons on the list).
Is k fixed or the variance? What are your data?  Specify a valid Null / 
Alternative combination. If you Null is variance = k (say) then you 
alternative is variance != k or if the alternative is variance > k, then 
your null is probably variance <= k

Uwe Ligges



  Alternative hypothesis is variance > k. Now if we know the true 
variance, then I would like to calculate the sample size required to 
produce certain power (for some
> significance). How do I do this ? I thought of using pwr.chisq.test, and I
contacted the author stephane champely, but he said his package can't do
this. Does anybody have an idea ?
> 
> Thanks
> Ati
> 
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