How would you suggest to do a survey across countries? Is it impossible?

Now you've hit on a problem I can get my mind around! The simple linguistic challenge of asking identical questions, with identical cultural and emotional content across cultures is impossible. Due to the same factors they try to measure here.

It's analogous to Heisenberg's uncertainty principle.

Excellent point.

"It Can't Be Just About Us"
--Frank Schnittger, ETian Extraordinaire