As history shows us, when colonization is voluntary, people will self-select better than any testing system. It's like those foolish attempts to control immigration to American based on the traits that were deemed desirable, when in fact the only trait that defines Americans historically is descended from somebody willing to give up everything to live there. Willingness is the single most important test.

Ender In Exile: Ender Series (ed. Hachette UK, 2012) - ISBN: 9781405515191