Kremlinologists beware. There is only a handful of countries left where outside observers can practise the arcane science of analysing regimes where political change is mandated behind closed doors and official data cannot be trusted. The quality of information on countries such as Cuba, though, is so poor that such analysis often seems more of an art than a science.

Take the size of Cuba’s economy. Calculations of gross domestic product vary significantly, from the government’s official figure of $54bn in 2007 to the Economist Intelligence Unit’s estimate of $45bn. The variations are due not just to the paucity of data but also to the authorities’ decision, since 2003, to value government services at market value, rather than at cost, as is the standard internationally. The EIU estimates that adjusting for this makes an cumulative 11 percentage point difference to the real GDP growth rate from 2004 to 2006.