Fun fact. In Argentina the previous government used to give subsidies to McDonald's to keep the BigMac cheap, so these numbers around the world comparing salary to the BigMac index would look better.
As a South African this hurts. We were ranked number 1 for purchasing power, and I've heard similar statistics from other sources. But the economy is shitting on us hard, and we are all struggling.
The one thing that isn't taken into account is things like tax wastage. I'd say easily 70 to 80% of our tax money is wasted by our inept government. So we have to fork out so much cash for basic things that other countries take for granted. It sort of feels like I pay tax twice. Once to the government which might as well be the money equivalent of /dev/null and another for private services which the municipality/government should be supplying, but what is offered is just too shitty to use.
So we may have the best purchasing power, but we have the least amount of money, so it doesn't help much.
INDEC is the government office in charge of carrying on the statistic (inflation, etc). They lied us for 4 years (with the previous government). They've shut it down completely 3 months ago (with the new government) and they're supposedly working to reopen it with legit information. We'll see.
Here are some sources to go with it: http://www.slate.com/blogs/moneybox/2012/05/01/why_big_macs_...
http://latitude.blogs.nytimes.com/2011/11/24/argentinas-big-...