L EE SHAU KEE moved to Hong Kong from mainland China in 1948, the year before China’s Communist Party seized control. In 1976 he set up a property company, Henderson Land Development, which helped to develop the tallest building on Hong Kong island and the hotel where Edward Snowden spilled America’s national-security secrets. Mr Lee is now the world’s 27th-richest person, according to Forbes, a business magazine. He and the 26 richer individuals have a combined worth of $1.39trn—more than the entire wealth of the poorest half of humanity.

This kind of startling comparison between the world’s most and least pecunious has been popularised by Oxfam, a charity. It draws on Forbes’s regular rankings of the world’s billionaires and the Credit Suisse Research Institute’s annual reports on household wealth. But the precision implied by such comparisons is spurious. The data on global wealth (which includes the net financial assets and property holdings of individuals) are too spotty to be rounded off to the nearest billionaire. Tony Shorrocks, the lead author of the Credit Suisse report, is reasonably confident that the poorest half of the world owns less than 1% of its wealth. But it is hard to be more exact than that.

The measurements are, however, improving. In last year’s Credit Suisse report, the richest 1% seemed to claim more than half of the world’s wealth (see chart). But new and improved estimates suggest the share of the one-percenters may have peaked or levelled off. Between 2016 and 2018, it fell in Brazil, Britain, France, Germany, India and Russia and flattened off in America, Canada, China, Italy and Japan.