Welcome, therefore, the iPod index. Its originator, the Australian Commonwealth Bank, claims that it is better because iPods are traded internationally. It goes without saying, too, that music is far more universal than burgers, with or without beef. Whats more, the input costs of burgers vary across the world, an infirmity that the iPod doesnt suffer from, even if taxes, scarcity premia and so on go against its claim to price uniformity. Nonetheless, the iPod index turns our notions of currency values upside down. Going by iPod prices, only three of 26 currencies are undervalued in relation to the US dollarthe Hong Kong dollar, Canadian dollar and Japanese Yenand the dollar ought to rise against most currencies. The Chinese yuan, for example, is overvalued by as much as 20% against the US dollar. The Big Mac Index, in contrast, shows Chinas currency undervalued by 56%. So you know which of the two brands might get to be the official soul-food at the Olympics. Indian exporters can also adopt the clickwheel in navigating their future: the rupee is overvalued by as much as 49% against the dollar, so it should fall. But then, the iPod index is only another imperfect indicator.