IT IS not quite the secret of eternal life. But it seems that, in America, public sector workers live slightly longer than those employed in the private sector. A new briefing from the Center for Retirement Research at Boston College examines the figures. It takes a cohort of 55-64 year of workers from 1983 and checks the mortality rate for such workers over the next 11 years.

When it comes to men, 17% of those in the public sector died over the following 11 years, compared with 17.6% of those in the private sector. For women, the difference was starker, and statistically significant; just 8.7% of public sector workers died, compared with 9.9% of those in the private sector. A second study covered a shorter follow-up period of just six years; the male gap disappears but female public sector workers still live longer.

Alas, simply applying for a government job will not add years to your life (although if the work is boring enough, it may feel like it). The main reason for the gap is education. In this particular cohort, 31.3% of male public sector workers had a full college degree; just 16.7% of private sector workers had the equivalent. For women, the gap was even starker; 28.3% of public sector workers had a degree against 7.6% in the private sector. Conversely, there were a lot more high school dropouts in the private sector than in the public sector. Educated people live longer.

Control for education and the gap disappears. Indeed, for men, controlling for education gives private sector workers an advantage, although that disappears if police and fire sector workers (the ones most in danger) are excluded. So the answer to longer life is not to work for the government but to get a degree.

Of course, the cost of providing pensions rises in line with longevity. That means public sector pensions are more expensive to fund. But while the public sector has been rightly criticised for overoptimistic assumptions about invetsment returns, they do allow for the better longevity of their workers; a separate paper by the CRR finds that plans are pretty good at keeping up to date with demographic change.