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From | Richard Williams <richardwilliams.ndu@gmail.com> |
To | statalist@hsphsun2.harvard.edu, "statalist@hsphsun2.harvard.edu" <statalist@hsphsun2.harvard.edu> |
Subject | Re: st: Missingness |
Date | Tue, 28 Aug 2012 09:20:19 -0500 |
At 02:42 AM 8/28/2012, Brendan Churchill wrote:
Dear Statalist UsersI am using some ordinal variables, which have some numeric missing values, in a multilevel model. In some previous research, I have seen researchers include a 'Missing' independent variable in their model to account for some of the 'missingness' - or rather to control for the missing values, but I don't quite understand how to do it in Stata or even if that's a good way to do it. I've tried to make a binary variable in which the missing values are coded 1 and the rest of the values are coded 0 but the model rejects this because it's collinear.Is this how you do it? Or is there a variable for the entire data set that is created to account for all missing variables?
In his green Sage book, "Missing Data", Paul Allison explains why this is usually (albeit not always) a bad idea. I briefly summarize the argument on pp. 4-5 of
http://www.nd.edu/~rwilliam/xsoc63993/l12.pdf ------------------------------------------- Richard Williams, Notre Dame Dept of Sociology OFFICE: (574)631-6668, (574)631-6463 HOME: (574)289-5227 EMAIL: Richard.A.Williams.5@ND.Edu WWW: http://www.nd.edu/~rwilliam * * For searches and help try: * http://www.stata.com/help.cgi?search * http://www.stata.com/support/statalist/faq * http://www.ats.ucla.edu/stat/stata/