The MI Procedure

(View the complete code for this example.)

This example uses logistic regression method to impute values for a binary variable in a data set with a monotone missing pattern.

In the following statements, the logistic regression method is used for the binary CLASS variable Species:

proc mi data=Fish2 seed=1305417 nimpute=15 out=outex4;
   class Species;
   monotone reg( Width/ details)
            logistic( Species= Length Width Length*Width/ details);
   var Length Width Species;
run;

The "Model Information"  table in Output 76.4.1 describes the method and options used in the multiple imputation process.

The "Monotone Model Specification"  table in Output 76.4.2 describes methods and imputed variables in the imputation model. The procedure uses the logistic regression method to impute the variable Species in the model. Missing values in other variables are not imputed.

The "Missing Data Patterns" table in Output 76.4.3 lists distinct missing data patterns with corresponding frequencies and percentages. The table confirms a monotone missing pattern for these variables.

When you use the DETAILS option, parameters estimated from the observed data and the parameters used in each imputation are displayed in the "Logistic Models for Monotone Method" table in Output 76.4.4.

The following statements list the first 10 observations of the data set Outex4 in Output 76.4.6:

proc print data=outex4(obs=10);
   title 'First 10 Observations of the Imputed Data Set';
run;

Note that a missing value of the variable Species is not imputed if the corresponding covariates are missing and not imputed, as shown by observation 4 in the table.