Stata The Stata listserver
[Date Prev][Date Next][Thread Prev][Thread Next][Date index][Thread index]

st: ice imputation

From   "Thy P. Do" <[email protected]>
To   [email protected]
Subject   st: ice imputation
Date   Mon, 11 Jul 2005 23:01:23 -0700 (PDT)

I am trying to utilize the 'ice' command for multiple imputation.  

My dataset is longitudinal with several time-varying covariates (eg, systolic bp, BMI) collected over 12 years.  The data are formatted in long format for use with stset.

I was informed that I needed to transform my data into wide format, with one row per subject (due to independence of observations in the imputation matrix).  By reformatting in wide, my time-varying covariates are now individual sequenced variables (eg, BMI1 BMI2...BMI12, BP1 BP2...BP12).  I also now have 65 total variables (only 9 of which have complete data).  After I have specified the imputation model (using all 65 variables), I get an error message of 'insufficient observations.'  I can't seem to find out what this is referring to.  Any suggestions?  Is there a maximum to the number of variables allowed in the imputation model?

Also, for continuous variables in the imputation model, do I need to check for normality?  If so, I assume I will need to transform the continuous variables and use the transformed variables in the imputation model?

Thanks for your help.

*   For searches and help try:

© Copyright 1996–2024 StataCorp LLC   |   Terms of use   |   Privacy   |   Contact us   |   What's new   |   Site index