R help - Jan 2009 - logistic regression - exp(estimates)?

hello.

I have a question on the interpretation of a logistic model.

is it helpful to exponentiate the coefficients (estimates)? I think I 
once read something about that, but I cannot remember where.
if so, how would be the interpretation of the exp(estimate) ?

would there be a change of the interpretation of the ANOVA table (or is 
the ANOVA table not really helpful at all?).


thanks for your time.

cheers,
gregor rolshausen

On 16/01/2009, at 1:50 AM, gregor rolshausen wrote:
> hello.
>
> I have a question on the interpretation of a logistic model.
>
> is it helpful to exponentiate the coefficients (estimates)? I think I
> once read something about that, but I cannot remember where.
> if so, how would be the interpretation of the exp(estimate) ?

	exp(beta_i) is the odds ratio for success when the i-th predictor
	x_i is incremented by 1.

	In particular if x_i is a 0-1 indicator variable then exp(beta_i) is
	the odds ratio for comparing the odds of success when x_i = 1 with
	the odds of success when x_i = 0.

	E.g. if x_i = 0 for Male and x_i = 1 for Female, and exp(beta_i) = 2,
	then the odds of success for Females are twice as great as the odds
	of success for Males.  I.e. Females are ``twice as likely'' to succeed
	as Males, all other things being equal.  (Which may or may not be a  
Good
	Thing, depending on what ``success'' really means. :-)
)
>
> would there be a change of the interpretation of the ANOVA table  
> (or is
> the ANOVA table not really helpful at all?).
	ANOVA tables are ***so*** 20th century!

		cheers,

			Rolf Turner

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