[R] Power sampling
Thomas Schönhoff
tom_woody at swissinfo.org
Thu Nov 18 11:22:29 CET 2004
Hello Uwe,
Uwe Ligges schrieb:
> Thomas SchÃ¶nhoff 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
population.
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 ?
Regards
Thomas
platform i386-pc-linux-gnu
arch i386
os linux-gnu
system i386, linux-gnu
status
major 2
minor 0.1
year 2004
month 11
day 15
language R
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