trickle down, flood up

During the 1980s... from every $100 worth of global economic growth, around $2.20 found its way to people living below the absolute poverty line. Bad enough, but a decade later that had shrunk to just 60 cents - the slice of the growth cake going to the poorest has been getting smaller. Meanwhile the actual mean income of those living under the absolute poverty line of $1 per day in Africa also fell, from 64 cents per person per day in 1981, to just 61 cents in 20011.

There has been, in effect, a sort of 'flood up' of wealth from poor to rich, rather than a trickle down. Perversely, it means that for the poor to get slightly less poor, the rich have to get very much richer. It now takes around $166 worth of global growth... to generate a single dollar of poverty reduction for people living below $1 a day, compared with around just $45 in the 1980s.

• 1. Shaohua Chen and Martin Ravallion (2004) How have the world's poorest fared since the early 1980s? Development Research Group, World Bank