m not sure if you'll classify it as "credible" but the wikipedia article on HPI shows a clear ranking of countries that roughly correlates to the minimum wage (higher the wage, lower the poverty ranking). Which.. Doesn't seem like rocket science.
And how did the process start? The poverty situation in the better off countries didn't start improving because of magical fairy dust.
One end pushes the other end, sure, but you've got to start it somewhere.
People and politicians took action and improved laws, businesses still kept going and the cycle repeats upwards.
I don't see that happening in the US. I don't mind if the change isn't minimum wage (not going to happen in America), but at least do /something/ positive.
Or perhaps countries with less poverty are able to support higher minimum wages?
http://xkcd.com/552/