ADF检验如下：滞后差分项选了0，检验出来已经是平稳的了。可是DW值很靠近0.，如果选1阶的话就不平稳了。还要选吗？
非平稳的话，能不能做Granger因果检验啊？

ADF Test Statistic  3.741163     1%   Critical Value*  -3.7343
      5%   Critical Value  -2.9907
      10% Critical Value  -2.6348
   
*MacKinnon critical values for rejection of hypothesis of a unit root.   
   
   
Augmented Dickey-Fuller Test Equation   
Dependent Variable: D(EC)   
Method: Least Squares   
Date: 05/27/11   Time: 20:28   
Sample(adjusted): 1986 2009   
Included observations: 24 after adjusting endpoints   
   
Variable Coefficient Std. Error t-Statistic Prob.  
   
EC(-1) 0.065068 0.017393 3.741163 0.0011
C -14.67619 98.81412 -0.148523 0.8833
   
R-squared 0.388826     Mean dependent var  325.5904
Adjusted R-squared 0.361045     S.D. dependent var  236.7266
S.E. of regression 189.2266     Akaike info criterion  13.40342
Sum squared resid 787747.3     Schwarz criterion  13.50159
Log likelihood -158.8411     F-statistic  13.99630
Durbin-Watson stat 0.800148     Prob(F-statistic)  0.001132