plm(): observations not used for modelling
Restoring some context:
DB wrote:
The fuction plm only uses 286 of these observations (also if the model is changed to first differences and the effect to individual) and omits 23 observations due to na.action, but in my dataset they do not contain NAs. Is this due to the Transformation used in the plm function? If it is of any help, these are the observations that are omitted (which obviously don't contain NAs): 176 1995 Spanien 177 1996 Spanien 178 1997 Spanien Verkehrstote_Quote Autobahnlaenge_Quote PKW_Quote$Value LKW$Value DW> I was surprised to [see] a "$" in a variable name. Are you sure that is not the source of your problems? dat <- data.frame(a$b = 1:3, d=1:3) Error: unexpected '=' in "dat <- data.frame(a$b =" DW> I would not expect the internal parsing routines to necessarily properly handle invalid column names.
On Nov 7, 2012, at 12:26 PM, Daniel Bab. wrote:
Thank you for your help. That's an interesting point, I haven't thought about that. Altough I would find it strange that I get a model, where just some observations are missing, if the problem is due to invalid variable names. That's the first thing I will try to change.
I wasn't able to fully explain it either. You provided no code and the data was in a form that suggested some pathology in preparation. So I probably should have just suggested that you post all the output from : dput(dataframe[ c( 90:110 , 370:400), ]) ... so we could see what rows looked like from both excluded and non-excluded categories.
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David Winsemius, MD Alameda, CA, USA