Table 1.

Estimated parameters and the Ljung–Box test in the optimal SARIMA model

Parameters	Coefficient	Standard error	T	P value	Residuals of SARIMA model
					Ljung–Box Q	P value
SARIMA (0.1,1)(0.1,1)12					0.358	0.549
MA(1)	−0.634	0.072	−8.860	<0.001
SMA(1)	−0.867	0.029	−29.582	<0.001

SARIMA, seasonal autoregressive integrated moving average; MA1, moving average, lag1; SMA1, seasonal moving average, lag1.