In Figure 9-10, the 1st portion (%) is 66, which means the SI EstimateOrders of System Model VI will use 66% of the data samples for estimationand the remainder of the data samples for validation.The SI Estimate Orders of System Model VI generates the predictionerror plot for the ARX model and the optimal A order and B order basedon the AIC criterion. By using the AIC criterion, the lowest prediction errorcorresponds to a model dimension of 19, as shown in Figure 9-9. For anARX model, the model dimension is equal to the sum of the A order,B order, and delay values. The SI Estimate Orders of System Model VIreturns the following optimal orders: