[R] Applying glm coefficients (Beginner Question)

[David Winsemius]

On Sep 20, 2012, at 6:55 AM, SirRon wrote:

> Hello,
> I am working with a dataset with three variables and one binomial parameter.
> The glm function provides coefficients for these three variables, e.g.
> -1.5 | 27.2 | -2.9
> 
> If I'm not mistaken, $fitted.values gives me an estimate of how likely my
> parameter is to be true/1 .

Not at all how I would have expressed it.

> I would like to apply these coefficients on
> other variables to predict the binomial parameter but I'm not sure how to
> make use of them.

On other instances of similarly measured variables? Then use the new data argument to predict().

> 
> To clarify a bit more I'm looking for a formula to calculate the chance that
> the parameter is true/1, based on the three variables/coefficients,
> something like
> 
> -1.5*V1+27.2*V2-2.9*V2

I am guessing you will be using the type="response" argument to predict(), but again is is not the case that this will be answer the question as you have expressed it and I have interpreted it. It is not going to return the probability that the "parameter is true", at least if the word "parameter" is what most people are calling "coefficient". 

?predict.glm

> I hope someone understands my awkwardly worded question and is able to help
> me out - thanks!

Awkwardly worded questions will get much better answers if they are accompanied by some test data.

-- 
David Winsemius, MD
Alameda, CA, USA