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From |
"Michael I. Lichter" <mlichter@buffalo.edu> |

To |
Nailing Xia <nailingxia@gmail.com> |

Subject |
Re: st: Multiple imputation showing missing values during imputation |

Date |
Tue, 09 Dec 2008 17:42:26 -0500 |

Nailing,

Michael Nailing Xia wrote:

Thanks, Michael. I checked the lower bound and upper bound variables as well as the interval variables for cases that Stata report imputed values being missing, but didn't find anything that looks strange. As a matter of fact, those cases are within an interval (i.e., both the lower bound and upper bound variables have a valid but different value, indicating that the interval variable should be imputed within that range) that needs an imputation with -intreg-. And here're the details of the dataset: I am using a longitudinal dataset that follows over 10,000 children for several years. The dataset has 5 waves, and in the model I included over 8,000 individuals. The -ice- command includes around 50 variables in total--as some of the variables are time-specific but some are not, the total number of variables are around 200. Options I used with -ice- include "sub", "passive", "cmd", and "interval". For all imputed variables (including categorical variables), I use -regress- (except for those that are included in the "interval" option and thus use -intreg-"). In "interval" option, I included 21 variables (out of over 200 variables included in -ice-), and 15 of them have the imputed value missing problem as described earlier. The number of missing cases range from 1 to 49. What happens is that Stata will replace the missing cases with mean and continue imputing. Then at cycle 6 when it is imputing one of the variable that has the imputed value missing problem, Stata shows that "convergence not achieved" and stops imputing (although I am not sure whether this problem relates to the imputed value missing problem). If you know anything about this problem, please help. Thanks a lot! Nailing Xia On Tue, Dec 9, 2008 at 3:23 PM, Michael I. Lichter <mlichter@buffalo.edu> wrote:Nailing, I suspect that you haven't gotten any responses because your question is (or appears to be) very specific to your data, but you don't say much about the specifics of your data. It might be helpful to describe the variables involved and the constraints you are putting on the imputed data using the -interval- option to -ice-. Here's a stab in the dark, though. Is it possible that one or more of your interval variables are missing for two cases in which your variable redlun5 is missing as well? If not, can you at least identify the two cases for which -ice- is failing to make an imputation and see if there is anything unusual about those cases' values on the other variables in the imputation? -ml Nailing Xia wrote:Hi, I am using -ice- for multiple imputation, and during the imputation process, Stata shows that values for several imputed variables that should have been imputed in previous cycle are actually missing. The actual error message reads as: "I found that 2 missing value(s) of redlun5 that should have been imputed were missing at cycle 2. Replacing value(s) with mean, dumping current data to file _ice_dump.dta and continuing." Anyone knows what seems to cause this problem? By the way, this problem did not exist when I imputed without using the -interval- option. But I checked my code for -interval- option, and it seems fine. Many thanks! Nailing Xia * * 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/-- Michael I. Lichter, Ph.D. Research Assistant Professor & NRSA Fellow UB Department of Family Medicine / Primary Care Research Institute UB Clinical Center, 462 Grider Street, Buffalo, NY 14215 Office: CC 125 / Phone: 716-898-4751 / E-Mail: mlichter@buffalo.edu * * 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/

-- Michael I. Lichter, Ph.D. Research Assistant Professor & NRSA Fellow UB Department of Family Medicine / Primary Care Research Institute UB Clinical Center, 462 Grider Street, Buffalo, NY 14215 Office: CC 125 / Phone: 716-898-4751 / E-Mail: mlichter@buffalo.edu * * 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/

**Follow-Ups**:**Re: st: Multiple imputation showing missing values during imputation***From:*"Nailing Xia" <nailingxia@gmail.com>

**References**:**st: Multiple imputation showing missing values during imputation***From:*"Nailing Xia" <nailingxia@gmail.com>

**Re: st: Multiple imputation showing missing values during imputation***From:*"Michael I. Lichter" <mlichter@buffalo.edu>

**Re: st: Multiple imputation showing missing values during imputation***From:*"Nailing Xia" <nailingxia@gmail.com>

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