SIX months after he became prime minister David Cameron initiated a survey of the nation's happiness. The country's economic strength had long been judged using indicators such as GDP, he said, in a speech in which he unveiled his plans. Yet, as Mr Cameron quoted Robert Kennedy as saying, GDP "does not allow for the health of our children, the quality of their education, or the joy of their play. It measures neither our wisdom nor our learning; neither our compassion nor our devotion to our country; it measures everything, in short, except that which makes life worthwhile." So the prime minister determined to identify a measure that did capture such intangibles.

On February 28th the Office of National Statistics announced the results. Its researchers asked people four questions: "how satisfied are you with your life nowadays?"; "to what extent do you feel the things you do in your life are worthwhile?"; "how happy did you feel yesterday?"; and "how anxious did you feel yesterday?". The data were analysed by whereabouts the respondents lived, by age and by sex, by socio-economic status and by employment status, and by whether people were married and whether they had any children.

For a people who complain that they "mustn't grumble", the survey found Brits to be relatively upbeat. Despite the country's economic woes, four out of five people said they were satisfied with their lives and three out of four said their lives were worthwhile. That chimes with earlier research from the OECD, a think tank, which found that rich countries tend to have populations who were more pleased with their lives than poor ones. It placed Britain above average in the happiness stakes, in a cluster of Anglophone countries that ranked just behind the sunny-natured Nordic countries, which topped the table.

The survey identified a trend seen in other countries: young adults tend to be happy until a dejection descends in middle age. The gloom lifts as people approach retirement, and oldsters who are in good health are just as satisfied with their lives as youngsters. Similarly young people become anxious on entering their thirties, and fret throughout the rest of their working lives. Those who have recently retired regain a sense of security.

People with partners are happiest of all, although singletons are happier than those whose marriage has ended through death or divorce. But children has no effect on contentment: childless couples rank the same as those with one, two, three, four or five or more children.

Londoners are more stressed than people living elsewhere in Britain, which could be due to the relatively small proportion of elderly people who live in the capital compared to its working age population or to the capital's high unemployment levels. Unsurprisingly the jobless are mostly dissatisfied with their lives. People from black and ethnic minority groups also expressed lower satisfaction levels than their white neighbours.

Developing government policy from such information is notoriously tricky, which may be why Tony Blair shied away from a similar idea when he was in power. That is because correlation is not causation: it may well be that happy people are likely to be married, for example, rather than marriage causing otherwise miserable souls to celebrate the good things in life. Yet the Young Foundation has made a start in trying to identify how consider well being when making local decisions. It may be easier to measure happiness than determine what causes it, but any data are welcome over none.