In the following SAS statements, is simulated by using this model, and the endogenous variable is set to be equal to . The MOMENT statement creates two more moments for the estimation. One is the second moment and the other is the first-order autocovariance. The NPREOBS=20 option instructs PROC MODEL to run the simulation 20 times before is compared to the first observation of . Because the initial is zero, the first is . Without the NPREOBS option, this is matched with the first observation of . With NPREOBS, this , along with the next 19 , is thrown away, and the moment match starts with the twenty-first with the first observation of . This way, the initial values do not exert a large inference on the simulated endogenous variables.