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From |
Richard Goldstein <richgold@ix.netcom.com> |

To |
statalist@hsphsun2.harvard.edu |

Subject |
Re: st: query on right-censored predictors/covariates |

Date |
Thu, 24 Jun 2010 13:33:44 -0400 |

Phil, sorry for not mentioning that I have uncensored observations as well as censored observations thank you for the info about the -ice- options -- the variables are *not* interval censored -- only the top is censored (e.g., I have the actual counts if they are less than 10, but have a value of 10 for any observation that has a count of at least 10; another example is that I have actual age if less than 90, but anyone who is at least 90 years of age has the value 90; the count variable is definitely not normally distributed Rich On 6/24/10 12:46 PM, Phil Schumm wrote: > On Jun 24, 2010, at 10:30 AM, Richard Goldstein wrote: >> I have a data set in which the outcome is *not* censored but at least >> 2 of the predictors (e.g., age which is "topcoded") are right censored >> and am looking for any literature dealing with this; right now I am >> leaning toward treating this as a missing data problem but I am >> certainly open to other solutions also >> >> re: use of multiple imputation, I would certainly need to constrain >> the imputed values to be at, or larger than, the current top value; I >> see no way to do this in either -mi- or -ice-: have I missed something? > > WRT imputation: If you have no uncensored observations in the dataset, > then this is difficult to handle, since you have to make an assumption > about what the form of the distribution is beyond the cutoff. If you're > willing to make a distributional assumption, then you can handle this > with -ice-, using the -interval()- option. More specifically, -ice- > will generate imputed values for an interval censored variable by > assuming that the underlying distribution is Normal; this means that you > can also use this for any variable that can be transformed to > approximately Normal (i.e., by generating the imputations on the > transformed scale, and then transforming back to the original). Note > that -ice- will even let you impose an upper limit on the imputed values > (i.e., so that you don't generate any predicted ages that are > unreasonably high). > > Perhaps if you had another dataset with uncensored versions of the > variables you are interested in imputing and substantial overlap with > the other variables in your model, you might be able to do something > else... > > > -- Phil * * 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: query on right-censored predictors/covariates***From:*Phil Schumm <pschumm@uchicago.edu>

**References**:**st: query on right-censored predictors/covariates***From:*Richard Goldstein <richgold@ix.netcom.com>

**Re: st: query on right-censored predictors/covariates***From:*Phil Schumm <pschumm@uchicago.edu>

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