RE: [Impute] Adding cases after imputation

[Nakanishi, Arline]

Seems to me that your answer would depend on what method was used to derive the imputed value.  In other words, would your imputed values change with the additional cases?  For example, if you were using a bootstrapping routine to pick imputed values, the additional cases would change your pool of possible values.  If so, then I would opt to reimpute for the original missing values under the presumption that the imputation would be improved.   Arline Nakanishi Amgen Inc. -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]On Behalf Of Cole, Jason Ph.D. Sent: Wednesday, April 07, 2004 9:32 AM To: Imputation Listserve ([EMAIL PROTECTED]) Subject: [Impute] Adding cases after imputation Hello all,   I have a question regarding the use of a second round of imputation.  If a group of data has had imputation conducted on it (say single-point imputation), and then more cases are added to the database (perhaps because the initial imputation was conducted for a midpoint analysis), what should be done for the additional analyses?  For example, should the original imputation values remain while just estimating the missing data for the new cases, or should all missing values be estimated (including a re-estimation of the original cases)?   Many thanks,   Jason   ************************************************************** Jason C. Cole, PhD Senior Statistician Department of Psychiatry and Biobehavioral Sciences Cousins Center for Psychoneuroimmunology 300 UCLA Medical Plaza, Room 3148 Los Angeles, CA 90095-7057 Tel: 310 267 4390 FAX: 310 794 9247 E-mail: [EMAIL PROTECTED] http://www.cousinspni.org **************************************************************

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