Multiple Imputation model and questions

Posted by jchaudhu on Oct 13, 2011; 6:09pm
URL: http://spssx-discussion.165.s1.nabble.com/Multiple-Imputation-model-and-questions-tp4900070.html

Hello - a couple questions about MI

1) When creating a database to impute missing values,  is it redundant to include subscales as well as summary score ( of the same measure) , if these are just auxiliary variables to inform the imputation?  I am worried about multicollinearity, but am not sure if that is really an issue with imputation.

2) What is the best way to determine how many datasets to impute?  (People in our lab have used Rubin's table of relative efficiencies, others have used the general rule to impute as many datasets as there is percentage of missing values (25% missing values, impute 25 data sets).