In my experience this is a terrible metric. The demographics that McDonalds is marketed in different countries varies enormously. I find in Western countries it is seen as unglamorous, cheap and quick food. Whereas when I was in India, for example, it is much more expensive than cheap food you can buy there, and therefore is seen much more as a nice place to go with your family (or girlfriends/boyfriend), and it tends to be middle class people who go there.

I was trying to think of a good alternative product for this index, but I really couldn't think of any single product that is marketed at exactly the same demographic in each country, as well as having comparable market penetration, and being desired by people to the same degree.

Ironically, Big Macs are on sale right now for 10 kuai in Beijing.