The commission of economists led by Joseph Stiglitz looking into the measurement of economic performance and social progress cited many flaws on Monday in existing indicators and made a host of proposals for better ones. Yet for all its complexity, their report has a simple message: one number cannot summarise everything.

Too often, the economists note, a narrow measure of market performance, such as gross domestic product, has been confused with broader measures of welfare. Governments may focus everything on increasing their GDP growth rate, treating it as an end in itself when it should not be.