Dear all,
I am trying to do panel cointegration test using xtwest command or using Westerlund(2007) error correction based panel cointegration test. Because of the cross-sectional dependence of our panel data I used the bootstrap option. But, when I use this command "xtwest debtgdp export , constant trend lags(1) leads(1) lrwindow(3)bootstrap(200)" in the same stata version in different time gives me different Robust P-value. Even, when I use Stata version 12.1 and Stata version 14.2 gives me totally different results.
I have written the result of Stata version 12.1 that I run in a different time and the same command. if you could provide me with some better suggestions on how to approach such a problem and what is the problem with it.
This is first result
xtwest export import , constant trend lags(1 2) leads(0 1) lrwindow(2)bootstrap(10)

Bootstrapping critical values under H0..........
Calculating Westerlund ECM panel cointegration tests..........

Results for H0: no cointegration
With 41 series and 1 covariate
Average AIC selected lag length: 2
Average AIC selected lead length: 1


Statistic Value Z-value P-value Robust P-value

Gt -2.128 1.880 0.970 0.100
Ga -3.983 7.560 1.000 1.000
Pt -18.004 -5.120 0.000 0.000
Pa -7.207 1.802 0.964 0.100

This also the second result different from the first one

xtwest export import , constant trend lags(1 2) leads(0 1) lrwindow(2)bootstrap(10)

Bootstrapping critical values under H0..........
Calculating Westerlund ECM panel cointegration tests..........

Results for H0: no cointegration
With 41 series and 1 covariate
Average AIC selected lag length: 2
Average AIC selected lead length: 1


Statistic Value Z-value P-value Robust P-value

Gt -2.128 1.880 0.970 0.200
Ga -3.983 7.560 1.000 1.000
Pt -18.004 -5.120 0.000 0.000
Pa -7.207 1.802 0.964 0.200