Hi,

I’m rather new to Amelia and have some troubles with it. Thus I would be very happy, if you could give me a hint. Here are my problems I’m dealing with:

I have two warning messages coming up when I try to run the imputation command on Amelia (using R) and I don’t know how to handle them:

· “You have a small number of observations, relative to the number, of variables in the imputation model. Consider removing some variables, or reducing the order of time polynomials to reduce the number of parameters.”

è What would be a good relation of observations to variables? Right now I have 292 observations and 121 variables in the data file. And I do not want to delete more variables, as they are pretty much the fundamental variables I want to do calculations with.

·         “The resulting variance matrix was not invertible.  Please check your data for highly collinear variables.”

è  Is Amelia not running properly in the case of collinear variables? Do I have to delete highly correlating variables or is there a way to work around? There are some variables that are very likely to correlate with each other, however I do not want to delete them from the sample as they will be important in further analysis.

Furthermore Amelia imputated 5 times, however data was only printed out in the last one of 5 excel sheets (using the command: write.amelia(obj=a.out, file.stem = "outdata", format = "csv")).

Do you have any idea why there is only data written to the last excel sheet? Or is this already the merged data sheet from all 5 imputations?

Cheers,

Stefanie

Dipl.-Psych. Stefanie Ringelhan

Lehrstuhl für Strategie und Organisation

Prof. Dr. Isabell M. Welpe

Fakultät für Wirtschaftswissenschaften
Technische Universität München
Leopoldstrasse 139
D-80804 München (Germany)

Tel.: +49-(0)89-289-24824
Email: s.ringelhan@tum.de

http://www.strategie.wi.tum.de