The Economist had a pretty scathing tear-down of indicies in the issue week before last. One article specifically criticises the Global Slavery Index, another is more satirical, but still well worth a read:
Also worth listening to the More Or Less podcast on BBC r4 where they interview the Economist journalist involved.
Specifically they found that the NGO behind the slavery index had taken some countries where there was no data and simply assumed that country had as much slavery as a similar country (nearby, similar population etc)
I'm disappointed that the USA didn't get credit for the vast world historical illegal/undocumented immigration levels the government has been inviting for decades. Millions work for less than survival wages with no legal rights and the government does nothing to discourage migration or employers.
Simple employer sanctions have proven effective in ending this kind of migration but US gov't imposes almost none.
Heck, even legal professional immigrants (H/L visas) don't have the right to change employers or resign.
If we had credit for all those millions, we'd be at the top of the league table here. Time for a recount. (We're number one.)
Specifically they found that the NGO behind the slavery index had taken some countries where there was no data and simply assumed that country had as much slavery as a similar country (nearby, similar population etc)
Then they ranked countries. And named and shamed.
It was not good statistics.