None of us are going to last for ever. Our prospects depend on our sex, our age, our lifestyle, our genes, and many other personal factors both known and unknown. Even with all this information we're all uncertain about the exact date of our death, but by looking at large groups of people who are like us, we can count how many die each year and so get an idea of the risks we face and how long we might live. Our risks can be summarised in different ways which are shown in the animation below.

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Each line represents a person's life - the line stops growing when they die. Try Sort by Age, and Hide the Living: the pattern you get is called a survival curve.

The dark bit of the line shows the hazard at the time they died - go on to the animation below to see what 'hazard' means and how it has changed over the last 25 years.

Hazard

This is the fraction of people who do not reach their next birthday: for example a male aged 60 has a 1% chance of not making his next birthday, while an 85-year old has an 11% chance of not making 86. It is traditionally known by the wonderful expression, the Force of mortality.

If applied to individuals, the hazard curve shows the annual risk of death, given you have survived up to now. Hazard curves typically have a 'bath-tub' shape - there is an early high-risk period immediately following birth, followed by long low period of annual risk, until accidents start kicking in for 17-year-old-boys , and then steadily increases.

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If you move the slider you can see how the hazard has changed over the last 25 years: the number of babies that die in their first year has halved, and the hazard for people in the 60's and 70's has dropped a lot. But people in their 90's don't seem to have benefited from all the improvements in lifestyle and healthcare.

Survival curves

Starting from your current age, say 40, these show the % of people of each sex who will reach each successive birthday, assuming the average risks currently faced in the UK. This curve steadily declines until all are dead. If you are willing to ignore all your personal information and simply consider yourself as 'average', then this assesses your chance of being alive at each year in the future.

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Put in your own age and sex and see what your life expectancy is, that is the average age at which people your age will die (assuming nothing changes in the future).

Relative risk

The graphs are based on data from the UK life-tables from 1982 to 2006 ukilt-1982-2006 , presented both as hazard and survival curves, as well as the recent results from the Norfolk EPIC study by Khaw and colleagues khaw:2008 . Click on Full Screen to get the full benefit.

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Force of Mortality shows how the hazard and survival curves can be got from looking at the ages at which people die.