Competing interests: I have read and understood the BMJ Group policy on declaration of interests and declare the following interests: The author has been provided funding by the Society of Actuaries and by the UK Institute and Faculty of Actuaries. In addition, a project led by the author, the Human Mortality Database, has received gifts from the Canadian Institute of Actuaries and from commercial insurance or re-insurance companies (SCOR, Hannover-Re, Reinsurance Of America, Munich-Re, and Milliman-France, Club Vita). The author is an unpaid volunteer member of the Society of Actuary Mortality and Longevity Steering Committee.