Urgent, Help plz!!!

[wind1985]

Hi, I' have some question on how to do the following with eviews:

1. I use ADF test to test uniroot and Ho is rejected when I test in first difference. So I suppose the data is I(1), and how do I correct it to make it stationary or I(0) with eview.

2. I am trying to find the okun's coefficient and so I need to work on the model:
log(gdp gap) = constant + betaxlog(unemployment gap) + [5 lags lengthof log(gdp gap)] + error
first I need to use sequential test to determine the appropriate lag of gdp gap on the right hand side of equation. Second, i think i need to use OLS to get Okun's coefficent. So how do I test the equation to find lags and also how to use write those gdp gap lag in the model and use OLS to estimate beta?

3. when is the time to use VEC model? After I run the VEC test, the table has 4 parts with the first part is CointegrationEq, and has all the coefficent for the variables. So i suppose those values are longrun relationship between exogenous variable and endogenous variable? And the second part is the error correction. What do those estimates/values stand for? Also, in the table there is a -1 after each variable [such as GDP (-1)], why? does that affect the coefficients? Say if the coefficent of GDP(-1) is -5, then the true value of coefficent in the model is 5?

Thank you very much.