Tuesday’s press was full of stories such as this suggesting that one in four current 16 year olds will live to be 100. I was a bit suspicious of this as it doesn’t seem that long since we were being told that current teenagers are an unhealthy bunch who only shift from their xboxes long enough to grab another portion of chips. Also the Government leapt onto the report as justification for hacking away at pension provision.
The claims appear to be based on this. The first thing to be noted is that the writer, James Evans, states clearly that the projections are based on extrapolating current trends and that such projections become increasingly unreliable the further into the future you take them – a caveat I have not noticed in the press coverage.
More seriously, this document includes a chart which shows how life expectancy at birth has increased over the last 60 years and projecting those increases into the future. The chart appears to show the male and female life expectancies at birth in 1951 to be 78 and 83 respectively and the current figures to be 88 and 92 respectively. This is purest bullshit. Further search found this which has a rather small graph which suggests that the 1951 life-expectancies were 65 and 72 respectively. The accompanying text states that the figures of 78 and 83 are expected to be achieved in 2021. Slight descrepancy there.
Here is the text of an email I have sent to Mr Evans:
Dear Mr Evans
I have been looking into the background behind yesterday’s press stories suggesting that 25% of current 16 year olds will live to be 100 and an internet search lead to your document http://research.dwp.gov.uk/asd/asd1/adhoc_analysis/2011/centenarians_by_age_groups.pdf
Chart 1 puzzled me as it suggests that in 1951 male life expectancy at birth was 78 and female 83. This seemed somewhat high and further search found http://www.parliament.uk/documents/commons/lib/research/rp99/rp99-111.pdf
a graph here suggests that the relevant life expectancies at birth were 65 and 72 respectively and the accompanying text says that the life expectancies of 78 and 83 will be achieved in 2021.
I am not a statistician so I wonder if you could explain this difference and further how the lower figures will change the projected number of centenarians.
I look forward to his reply.