Allan Reese has written about the case of the woman convicted of killing her two
children, apparently partly on the basis of a statistical argument.
I thought members might be interested in some data. In 1996, the most recent
year for which data are available, there were 649,489 live births in E&W.
There were 4,959 deaths in the first year of life, including 394 sudden infant
deaths (SIDS or cot deaths) and 14 homicides. Thus the probability of a cot
death is 1 in 649489/394 = 1,648. If deaths were independent, which they are
not because there are familial risk factors, the risk that a fimily of two
babies would have two cot deaths would be 1 in 1,648*1,648 = 2,715,904.
Presumably some other adjustment was applied for social factors as the figure
given in the press is said to apply to `well-to-do families'.
But the same calculation for homicide gives a risk that that two baies will both
be murdered as one in (649489/14)^2 = 2,152,224,291. If the first figure is
relevant, so is the second. As Allan says, neither is relevant.
Martin
.
Prof J M Bland
Dept of Public Health Sciences
St George's Hospital Medical School
London SW17 0RE, UK
Tel 0181-725 5492
email [log in to unmask]
-----------------------------------------------------------------
This mail sent through SGHMS Webmail: https://webmail.sghms.ac.uk/
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
|