A Comparative study of unit roottests with panel data and a new simple test（5）

G. S. Maddala and Shaowen Wu

(H. D. Thoreau: Walden)

A Comparative study of unit root tests withpanel data and a new simple test --5

1，  using all i andt. The resulting t-statistic is：

2，isthe average lag length used in the individual ADF regression.

3，  Since the test statistic is not centered atzero, Levin and Lin suggest using the following adjusted t-statistic:

（学习待续）