How to measure North Korea’s economy

FACTS about the North Korean economy are not so much alternative as non-existent. The country has never published a statistical yearbook. If it did, no one would believe it. Nicholas Eberstadt of the American Enterprise Institute, a think-tank, calls analysis of its economy “essentially pre-quantitative”.

The most-cited estimate of the size of the economy comes from South Korea’s central bank. Its methodology is opaque but is based, at least in part, on the South Korean intelligence agency’s estimates of the North’s physical output, which is then translated to South Korean prices. But it is hard to estimate market valuations for goods that are not traded on the market, and physical goods make up only a fraction of overall economic output. Another technique is to “mirror” statistics from the country’s trading partners. But most North Korean trade is with China, where statistics are unreliable.

The advent of satellite imaging has helped, providing researchers with better estimates of manufacturing output, coal production and urbanisation. Yet another strategy is to work out national...