Thank you for the advice. For the density08 variable, that is population density in year 2008. I also have population densities for year 2000, so I could put them both in, and interpolate between them for the times that are covered by the panel (2000-2008), and then just have a "density" column that will vary both over time and across various courts. I would assume that this would fix the problem of density not showing up in my coefficients list, although I think it is more of an econometrics issue :)
Thanks again, -stephen On Tue, May 19, 2009 at 3:35 PM, Achim Zeileis <achim.zeil...@wu-wien.ac.at> wrote: > On Tue, 19 May 2009, Stephen J. Barr wrote: > >> Ah, thank you for the help, and for the explanation of what is going >> on. I suppose I will have to reload my data with plm.data set such >> that RATE is not a factor. > > plmWithDensity$RATE <- as.numeric(as.character(plmWithDensity$RATE)) > > should suffice. > >> For my time index, will >> 2000,2000.25,2000.5, etc. work? Meaning 2000 quarter 1, 2000 quarter >> 2, etc? Or is there some special way that I need to format the time? > > That's ok. Internally, plm.data always stores it as a factor anyway. > > Best, > Z > >> Thanks, >> -stephen >> ========================================== >> Stephen J. Barr >> University of Washington >> WEB: www.econsteve.com >> ========================================== >> >> >> >> On Tue, May 19, 2009 at 4:39 PM, Achim Zeileis >> <achim.zeil...@wu-wien.ac.at> wrote: >>> >>> On Tue, 19 May 2009, Stephen J. Barr wrote: >>> >>>> Hello, >>> >>>> I am working on a data set (already as a plm.data object) located >>>> here: http://econsteve.com/arch/plmWithDensity.Robj >>>> >>>> With the following R session: >>>>> >>>>> library(plm) >>>> >>>> ... >>>>> >>>>> load("plmWithDensity.Robj") >>>>> model <- plm(RATE ~ density08, data=plmWithDensity) >>>> >>>> Error: subscript out of bounds >>>> >>>> I am not understanding the "subscript out of bounds" error, as this is >>> >>> I agree that the error is not very meaningful but the problem is due to >>> your >>> data: density08 does not vary within your id variable (COURT), hence the >>> default within model cannot be estimated. And it is also the reason why >>> density08 gets no coefficient in a larger model. >>> >>> Also note that your RATE variable is a factor...I'm pretty certain you >>> want >>> a numeric variable here! >>> >>> Yves & Giovanni: What happens in the code is that the model.matrix() >>> method >>> silently omits the column from the regressor matrix. Hence, this goes >>> unnoticed in the larger model and results in a regressor matrix without >>> any >>> columns in the case above. Thus, the subscript error. >>> >>> hth, >>> Z >>> >>> >> >> > ______________________________________________ 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.
