With a gross domestic product of little more than $200 (£110; €155) per person, Tanzania is among the world's poorest countries. Spending on health care for each citizen amounts to around $10 a year. Any increase in such a small sum must be better than nothing; but who could have imagined that less than one extra dollar would bring significant improvement?

Surprising or not, that's what the organisers of an innovative health scheme have shown. The effect of that extra dollar in two districts of Tanzania has been a substantial fall in infant mortality and an improvement in the health of adults. Such are the fruits of the Tanzanian Essential Health Intervention project (TEHIP), the first full account of which, Fixing Health Systems, was published last month.

Inspired by a 1993 World Bank report on the effectiveness of health interventions and funded by Canada's International Development Research Centre, the project was an attempt to put theory into practice. It was designed as a test of evidence based health planning. In particular it aimed to explore the feasibility of having district heath officials allocate resources not by formulas worked out in a remote central ministry but according to …