Hi Melissa, I would highly encourage you to read [1]. It would be extremely beneficial for your understanding of the type of models you should use in a situation like yours (count data).
Best regards, Jorge.- [1] cran.r-project.org/web/packages/pscl/vignettes/countreg.pdf On Wed, Apr 4, 2012 at 1:10 AM, Melrose2012 <> wrote: > Thank you for your reply. > > I do understand that I am working in log space with the default link > function of the binomial being "logit." My problem is, I thought that they > way I had written the code, when I did the "lines" command, it should plot > the best-fit line (found by 'glm') on top of my graph. As you can see, > however, this clearly did not work and I am off by several factors of > magnitude. I am not sure if the problem lies in the way I have done the > 'glm' or in the plotting. > > If I understand the function correctly, when I do 'glm' of family=binomial, > I am working in log space (hence the link function default being "logit.") > If this is correct, then doesn't either my data have to be converted to log > space also or the results of my 'glm.fit' be converted to linear space > (i.e. > using 'inv.logit' from the boot library)? This was my thought process > behind plotting the data as log (I tried several other obviously useless > iterations of various scalings.) It appears that you can not do an > inv.logit on the result from the 'glm' command. > > If I try to do this: inv.logit(glm.fit) > I get an error saying: Error in plogis(q, location, scale, lower.tail, > log.p) : Non-numeric argument to mathematical function > > I'm pretty sure this is a limitation in my understanding of exactly what R > is doing in this logistic regression and I am having a hard time finding > help online or in the R help files that helps me to decipher this problem. > > Can anyone tell me if I have set up the 'glm' wrong or if the error is in > how I am trying to plot the best-fit line on the data? > > I am new to these sorts of statistics and data manipulation, so I > acknowledge my ignorance and appreciate whatever help anyone can give me. > > Thank you again! > > Cheers, > Melissa > > -- > View this message in context: > http://r.789695.n4.nabble.com/logistic-regression-tp4530651p4530959.html > Sent from the R help mailing list archive at Nabble.com. > > ______________________________________________ > R-help@r-project.org mailing list > 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. > [[alternative HTML version deleted]] ______________________________________________ R-help@r-project.org mailing list 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.
