Table 4. Robustness test result.

Variable	SDM-lag	SDM-time
ln PSI	0.311*	0.563**
ln GDP	0.214**	0.912***
ln SISD	0.313*	0.884**
ln SPI	-0.105	1.312***
ln PSI * W	-	0.635
ln GDP * W	-	-0.101*
ln SISD * W	-	0.118
ln SPI * W	-	0.382**
R2—ad	0.515	0.235
Lag − likehood	389.12	637.32
Individual effect	Control	Control
Time effect	Control	Control
Sample size	3420	3420