Table 1. Parameter estimates of seasonal autoregressive integrated moving average model .

	ar1	ar2	ma1	ma2	ma3	sar1	sma1
Coefficient	-1.719	-0.903	1.124	-0.109	-0.615	-0.164	-0.721
t-stat	-25.732	-15.677	13.896	-1.049	-8.855	-1.602	-8.620
P value	0.001	0.001	0.001	0.293	0.001	0.100	0.001

z_t=-1.719 z_t-1-0.903 z_t-2-0.164 z_t-12+ ${\epsilon }_t$ +1.124 ${\epsilon }_{t-1}$ -0.109 ${\epsilon }_{t-2}$ -0.615 ${\epsilon }_{t-3}$ -0.721 ${\epsilon }_{t-12}$

z_t=dsbructr