I want to use PMM(pattern mixed model) to impute missing data, so I used the MNAR modelobs to specify the observations used to build the imputation model, but i found if the observations in the dataset but are NOT specified as modelobs change, the imoutation model will change too, it confused me, from my understanding, the imputation model is derived from the observations i specified in the option 'modelobs=x', so it will not be impacted by the other observations, but it seems this is not the truth. Here are some examples: the only difference between below 2 codes is the input dataset, in code 2, more observations are included in the input dataset. bothe of the 2 codes use observations 'model_ob='M4'' to specify the observations used to derive the imputation model. in the SAS output, the parameters that are estimated from the same observations used to build model are different, why ? ps: i tried to procude the below pictures in English version SAS, but failed due to codeing issue, hope the CHINESE charactors doesn't affect your reading.
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