For quite some time The Economist has used the Big Mac Index. This is a tool for estimating how over or under-valued exchange rates are between countries. It works on the assumption that Big Macs are the same in every country, so they should cost the same. This theory (known as purchasing power parity) is thought to be a long-term indicator of value. So for example, if a Big Mac costs US$2.00 in the USA and HK$14 here in Hong Kong, then according to the theory the HK/US exchange rate should be US$1=HK$7. But in fact US$1 buys HK$7.80 on the foreign excahnge market so the HK$ is undervalued by 11.4%.

There are some big problems with this model. One of the biggest is it doesn't account for one of the biggest parts of the economy: the services sector. So I got to thinking. What is a service that is the same everywhere in the world? What service's rates will be directly comparable, where the quality of the service is the same in each country? The answer's obvious.

So I hereby propose a new Global Prositution Index (GPI). A set of highly trained technicians will volunteer to collate the cost of a prostitute's services in every country in the world. We will collect and compare the results and publish this sure-fire method of finding which currencies are over or under-valued. Or at worst which countries are cheapest for a blow-job.

Of course quality control will be an issue. That's why I'm looking for volunteers. Anyone?