[R] Logistic Regression output baseline (reference) category
David Winsemius
dwinsemius at comcast.net
Wed Mar 16 02:26:21 CET 2016
> 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.
>
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>
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David Winsemius
Alameda, CA, USA
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