[R] 2k-factorial design with 10 parameters

[Petr Pikal]

On 30 Nov 2004 at 12:59, Sven wrote:

> Hi,
> 
> I'd like to apply a 2^k factorial design with k=10 parameters.
> Obviously this results in a quite long term for the model equation due
> to the high number of combinations of parameters.
> 
> How can I specify the equation for the linear model (lm) without
> writing all combinations explicitly down by hand? Does a R command
> exist for this problematic?

Hi Sven

from
?lm

The specification 'first*second'
     indicates the _cross_ of 'first' and 'second'.  This is the same
     as 'first + second + first:second'

and from

?formula

## Create a formula for a model with a large number of variables:
     xnam <- paste("x", 1:25, sep="")
     (fmla <- as.formula(paste("y ~ ", paste(xnam, collapse= "+"))))

If you change 1:25 to 1:10 and collapse to * and use fmla in your 
model you will get what you want (I suppose). But I woder if it 
has any sense.

Cheers
Petr

> 
> Thanks for your help in advance,
> Sven
> 
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Petr Pikal
petr.pikal at precheza.cz