Re: [R] Logistic Regression output baseline (reference) category
> On Mar 25, 2016, at 10:19 PM, Michael Artz 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. It represents all of the X variables at their reference levels. There are no individual intercepts on a variable-by-variable basis. You accepted the notion of "baseline" You cannot parcel out single variable intercepts. What would they actually mean anyhow? > Is there a way in R, to extrapolate the individual x variable > intercepts from the equation somehow. If you describe the process by which that could be calculated, we might have basis for discussion, but as it is I think you still need to be studying the theory more. I don't intend any further resspones on R-help where these questions are off-topic, so you should direct any further questions to stats.stackexchange.com > > > On Tue, Mar 15, 2016 at 8:26 PM, David Winsemius > wrote: > >> >>> On Mar 15, 2016, at 1:27 PM, Michael Artz >> wrote: >>> >>> Hi, >>> I am trying to use the summary from the glm function as a data source. >> I >>> am using the call sink() 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. >> David Winsemius Alameda, CA, USA __ R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
Re: [R] Logistic Regression output baseline (reference) category
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 wrote: > > > On Mar 15, 2016, at 1:27 PM, Michael Artz > wrote: > > > > Hi, > > I am trying to use the summary from the glm function as a data source. > I > > am using the call sink() 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. > > > > > [[alternative HTML version deleted]] > > > > __ > > R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see > > https://stat.ethz.ch/mailman/listinfo/r-help > > PLEASE do read the posting guide > http://www.R-project.org/posting-guide.html > > and provide commented, minimal, self-contained, reproducible code. > > David Winsemius > Alameda, CA, USA > > [[alternative HTML version deleted]] __ R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
Re: [R] Logistic Regression output baseline (reference) category
> On Mar 15, 2016, at 1:27 PM, Michael Artz wrote: > > Hi, > I am trying to use the summary from the glm function as a data source. I > am using the call sink() 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. > > [[alternative HTML version deleted]] > > __ > R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see > https://stat.ethz.ch/mailman/listinfo/r-help > PLEASE do read the posting guide http://www.R-project.org/posting-guide.html > and provide commented, minimal, self-contained, reproducible code. David Winsemius Alameda, CA, USA __ R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
Re: [R] Logistic Regression output baseline (reference) category
The reference category is aliased with the constant term in the default contr.treatment contrasts. See ?contr.treatment , ?C, ?contrasts If you don't know what this means, you should probably consult a local statistical resource or ask about linear model contrasts at a statistical help website like stats.stackexchange.com. This list is for R programming questions. Cheers, Bert Bert Gunter "The trouble with having an open mind is that people keep coming along and sticking things into it." -- Opus (aka Berkeley Breathed in his "Bloom County" comic strip ) On Tue, Mar 15, 2016 at 1:27 PM, Michael Artz wrote: > Hi, >I am trying to use the summary from the glm function as a data source. I > am using the call sink() then > summary(logisticRegModel)$coefficients then sink(). The independent > variables are categorical and thus there is always a baseline value for > every category that is omitted from the glm output. I am interested in how > to get the Z column for all of the categorical values. I don't see any row > for the reference category. How can I get this Z value in the output? > > [[alternative HTML version deleted]] > > __ > R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see > https://stat.ethz.ch/mailman/listinfo/r-help > PLEASE do read the posting guide http://www.R-project.org/posting-guide.html > and provide commented, minimal, self-contained, reproducible code. __ R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
