[R] Power sampling

Thomas Schönhoff tom_woody at swissinfo.org
Thu Nov 18 11:22:29 CET 2004

Hello Uwe,

Uwe Ligges schrieb:
> Thomas Schönhoff wrote:

> You have to tell us for which test you are going to calculate the power 
> ... (and there might be nothing, since calculating the power precisely 
> is not always that easy).

Given my example from the first message I asked for a function which 
enables me to calculate a reasonable sample size.

I don't know the true mean or standard deviation of the population, I 
only know:

n= 5.000.000 observations over 70 variables

determined alpha = 0.01

I want to know how to generate a sufficiently sized sample based upon 
above mentioned facts to make some valid predictions regarding my 

All I can hink of for now is that a two-tailed power test is required 
to find out if H0= random effect  or H1= no random effect hypothesis 
is accepted/rejected.

In epidemiological studies this situation is described like this:

How many cases do I have to include in my sample (s) to gain some 
representative results from a unknown population (=true mean, 
std-deviation etc.)?

How can I approach a situation like this in R ?



platform i386-pc-linux-gnu
arch     i386
os       linux-gnu
system   i386, linux-gnu
major    2
minor    0.1
year     2004
month    11
day      15
language R

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