st: Imputation vs substitution with mean

[James Bernard <jamesstatalist@gmail.com>]

Hi All,

I have a longitudinal dataset with a dependent variable of count type.
Mu independent variable are of continuous and categorical type.

My independent variables have many missing values. I want to
substitute the missing values.

One way is to go through what I found out to be "imputation".

I heard that an easier approach is substituting the values with group
mean/population mean. Is this very different form imputation done by
-mi-command in Stata?

Thanks in advance,

James
*
*   For searches and help try:
*   http://www.stata.com/help.cgi?search
*   http://www.stata.com/support/faqs/resources/statalist-faq/
*   http://www.ats.ucla.edu/stat/stata/