ADF test on Eviews 4

[hatoqaia]

Hello ,

please i have a question and I'll be appreciated if anyone help me :

i am running a unit root test ( ADF test ) in order to check if the variables are stationary or not
unlike the other versions of Eviews : in the Unit root test screen i have to enter the lagged difference and i am confusing what should i have to put ? 0,1, when i want to test the variables at level

and when i want to test the variables at first difference what lagged difference should i choose ?

[EViews Glenn]

The lagged differences are the whitening variables, not the variable to test. The documentation describes the basic ideas behind the two different concepts