变量	差分阶数	t	P	AIC	临界值
变量	差分阶数	t	P	AIC	1%	5%	10%
yield (t)	0	−2.534	0.107	66.499	−4.939	−3.478	−2.844
	1	−1.176	0.684	60.32	−4.473	−3.29	−2.772
	2	−3.063	0.029	63.819	−4.665	−3.367	−2.803