R help - Feb 2012 - Finding all the coefficients for a logit model

Let's say I have a variable, day, which is saved as a factor with 7 levels,
and I use it in a
logistic regression model. I ran the model using the car package in R and
printed out the
results.

mod1 = glm(factor(status1) ~ factor(day), data=mydat,
family=binomial(link="logit"))
print(summary(mod1))

The result I get is:

Coefficients:
                     Estimate Std. Error z value Pr(>|z|)
(Intercept)           -0.4350     0.0379  -11.48   <2e-16 ***
factor(day)Monday     -0.6072     0.0479  -12.69   <2e-16 ***
factor(day)Saturday    0.5964     0.0559   10.67   <2e-16 ***
factor(day)Sunday      1.1140     0.0627   17.78   <2e-16 ***
factor(day)Thursday   -0.4492     0.0516   -8.71   <2e-16 ***
factor(day)Tuesday    -0.9331     0.0496  -18.82   <2e-16 ***
factor(day)Wednesday  -0.8575     0.0486  -17.63   <2e-16 ***


It seems that Friday is being used as the baseline, but I want to know

how I can acquire the coefficient for the baseline (friday)?


I ran mod1$coefficients, but that didn't do the trick.


Can anyone help.


Thank you,

Abraham M.

	[[alternative HTML version deleted]]

Add -1 to your glm to remove the intercept term -- that will force
Friday to have its own coefficient.

E.g.,

dg <- data.frame(value = rnorm(28), day = letters[1:7])
lm(value ~ day, data = dg)
lm(value ~ day - 1, data = dg)

Michael

On Thu, Feb 9, 2012 at 6:58 PM, Abraham Mathew <abmathewks at gmail.com>
wrote:
> Let's say I have a variable, day, which is saved as a factor with 7
levels,
> and I use it in a
> logistic regression model. I ran the model using the car package in R and
> printed out the
> results.
>
> mod1 = glm(factor(status1) ~ factor(day), data=mydat,
> family=binomial(link="logit"))
> print(summary(mod1))
>
> The result I get is:
>
> Coefficients:
> ? ? ? ? ? ? ? ? ? ? Estimate Std. Error z value Pr(>|z|)
> (Intercept) ? ? ? ? ? -0.4350 ? ? 0.0379 ?-11.48 ? <2e-16 ***
> factor(day)Monday ? ? -0.6072 ? ? 0.0479 ?-12.69 ? <2e-16 ***
> factor(day)Saturday ? ?0.5964 ? ? 0.0559 ? 10.67 ? <2e-16 ***
> factor(day)Sunday ? ? ?1.1140 ? ? 0.0627 ? 17.78 ? <2e-16 ***
> factor(day)Thursday ? -0.4492 ? ? 0.0516 ? -8.71 ? <2e-16 ***
> factor(day)Tuesday ? ?-0.9331 ? ? 0.0496 ?-18.82 ? <2e-16 ***
> factor(day)Wednesday ?-0.8575 ? ? 0.0486 ?-17.63 ? <2e-16 ***
>
>
> It seems that Friday is being used as the baseline, but I want to know
>
> how I can acquire the coefficient for the baseline (friday)?
>
>
> I ran mod1$coefficients, but that didn't do the trick.
>
>
> Can anyone help.
>
>
> Thank you,
>
> Abraham M.
>
> ? ? ? ?[[alternative HTML version deleted]]
>
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