Dear Bill Gates,

We have never met, but your annual letter (coinciding with your Davos speech) seemed to be addressed directly to me. Your aim is to critique books with titles such as “how rich countries got rich and why poor countries stay poor”, and I did write a book with almost exactly that subtitle. You go on to say “thankfully these are not bestsellers because the basic premise is false”. I am afraid you are right to say my book is not a bestseller, but wrong to say its premise is false.

Taking the year 2001, I used two different measures of whether a country was rich: the market value of per capita output (a measure of productivity) and the average consumption of the inhabitants (a measure of material standard of living). The two rankings differ, though not by much; Switzerland had the highest productivity and the US the highest consumption.