In Forbes, Tim Worstall explains a misunderstanding of Ricardo’s Iron Law of One Price on the part of the Guardian:
This is a fun little bit of data calculation and visualisation. It’s a database and then mapping of the global price list for Apple’s iPhone 5s. And there are two interesting ways of using it. The first is simply to look at how prices differ around the world:
You can do this in USD or GBP as you wish. And this can be used to explore the violations of Ricardo’s Iron Law of One Price. Which is where David Ricardo insisted that the prices of traded goods would inevitably move to being equal all over the world. Well, equal minus the transport costs of getting them around the world. And transport costs for an iPhone are trivial: it would be amazing if Apple were paying more than a couple of dollars to airfreight one to anywhere at all. So, we would expect prices to be the same everywhere: but they obviously are not.
However, when The Guardian reports on this something appears to go wrong. Not their fault I suppose, it’s about economics and lefties never really do get that subject. But here:
Similar to the way the Economist tracks the cost of the ubiquitous McDonalds burger across countries, nations and states, Mobile Unlocked tracked the price of the iPhone 5S across 47 countries in native currencies with native sales tax, and then converted those prices into US dollars (USD) or British pounds (GBP).
No … the Big Mac Index operates entirely and exactly the other way around. We need to make the distinction between traded goods and non-traded goods. The Iron Law only works on traded goods. What we’re trying to find out with PPP calculations is what are the price differentials of non-traded goods? Which is why the Big Mac is used. It is (supposedly at least) exactly the same all over the world. It is also made almost entirely from local produce bought at the local price in local markets. US Big Macs use American beef, Argentine ones Argentine and so on. So we get to see the impact of local prices on the same product worldwide. That’s what we’re actually attempting with that Big Mac Index. The Economist then goes on to compare the prices of this non-traded good with exchange rates and attempt to work out whether the exchange rates are correct or not.
This is entirely different from using the price of a traded good to measure local price variations. For what we’re going to be measuring here is what interventions there are into stopping the Iron Law working, not what local price levels are.