Logistic Regression output baseline (reference) category

On Mar 25, 2016, at 10:19 PM, Michael Artz <michaeleartz at gmail.com> wrote:

Hi,
 I have now read an introductory text on regression and I think I do
understand what the intercept is doing.  However, my original question is
still unanswered.  I understand that the intercept term is the constant
that each other term is measured against.  I think baseline is a good word
for it.  However, it does not represent any one of the x variables by
itself.

 Is there a way in R, to extrapolate the individual x variable
intercepts from the equation somehow.

On Tue, Mar 15, 2016 at 8:26 PM, David Winsemius <dwinsemius at comcast.net>
wrote:

On Mar 15, 2016, at 1:27 PM, Michael Artz <michaeleartz at gmail.com>

wrote:

Hi,
 I am trying to use the summary from the glm function as a data source.

I

am using the call sink(<some file>) then
summary(logisticRegModel)$coefficients then sink().

Since it's a matrix you may need to locate a function that write matrices
to files. I seem to remember that the MASS package has one.

The independent
variables are categorical and thus there is always a baseline value for
every category that is omitted from the glm output.

Well, it's not really omitted, so much as shared among all variables. For
further reading in the halp pages consult:

?model.matrix
?contrasts
?contr.treatment

But you probably need to supplement that with an introductory text that
covers R regression defaults.

I am interested in how
to get the Z column for all of the categorical values.

The Z column? You meant the "z value" column. Again, since it's a matrix
you need to use column indexing with "["

summary(logisticRegModel)$coefficients[  , "z value"]

Read up on the summary function for glm objects at:

?summary.glm

I don't see any row
for the reference category.

What do you imagine the (Intercept) row to be doing? If you are having
difficulty understanding this (which is not really an R-specific issue)
there are probably already several explanations to similar questions on:

http://stats.stackexchange.com/

How can I get this Z value in the output?

Asked and answered.