Bala: one could multiply impute the missing values using a program such as IVEware (see my colleague Raghunathan's U Michigan web site). You might explore PM models, but I think the MAR analysis is the default
BTW, under MAR there is not much information in the cases with outcome missing for the regression on all the covariates -- in the special case with all covariates observed, no information at all. So I am skeptical that imputing the cases with missing outcomes will have much pay-off. Rod On Mon, 25 Oct 2004, Balasubramani, G.K. wrote: > Hello all, > > We have a multivariate missing data(outcome is a continuous measure and > missing occurs in both outcome as well as in covariates) and the it > follows the assumption of MNAR. We are trying to do the pattern mixture > model approach as suggested by Little (1993) in his JASA paper. But we > had some difficulty of doing that. I can briefy explain below our data > structure: > > The data set consists of four sets of patterns: > > 1. Non- missing outcome(continuous measure) with all the values of the > covariates are available > 2. Non-missing outcome with one or more vaues of the covariates are > missing > 3. Missing outcome with all the values of the covariates are available > > 4. Missing outcome with one or more vaues of the covariates are > missing. > > We modelled on non-missing outcome using the first two groups and > estimated the parameters and using these estimated parameters, we > predict the missing outcome, but for only with all the values of the > covatiate. We cannot be able to find out the values for the missing > outcome with missed covariate values. > > In this type of situation, how to model this case using the data > patterns in 3 and 4. Is there any method available for the missing > covarites for imputation. > > Any suggestions. > > Thanks in advance. > > Bala > ___________________________________________________________________________________ Roderick Little Richard D. Remington Collegiate Professor (734) 936-1003 Department of Biostatistics Fax: (734) 763-2215 U-M School of Public Health M4045 SPH II [email protected] 1420 Washington Hgts http://www.sph.umich.edu/~rlittle/ Ann Arbor, MI 48109-2029
