More accurately, he--for, like, the thousandth time--points out how the media fail to take this care.
My interest in this issue has increased, as I'm currently making my first forays into using serious quantitative data for a historical study. Indeed, I spent much of the last two days trying to come to grips with pivot tables so that I can make some sense of the information I've been carefully collating and entering into a spreadsheet.
Some of you may have gotten drowsy simply reading those last two sentences, and not long ago I might have been with you; however, I'm starting to find something exciting about making numbers do various little dances. (And, after a period of wanting to throw my laptop against the wall out of frustration, I seem to have gotten my tables to do what they are supposed to.)
I have the good fortune of working with a colleague who knows his way around numbers, and I've become increasingly aware of how much discipline is required in teaching your figures the requisite dance steps. This is especially so in cases when you're trying to use that data to tell you about such nebulous topics as 'cultural attitudes' or 'social life'.
The specific topic of Goldacre post was a recent spate of stories suggesting that there had been a shift toward a more 'caring society' based on a figure showing a greater number of births of children with Down syndrome. The logic behind this, I think, is that the growth in Down syndrome births showed a greater willingness to bring such pregancies to term. A number of media sources took this story and ran with it, expanding on the notion that this figure might tell us something meaningful about social attitudes.
And, yes, maybe they have changed in some positive ways.
But Goldacre points out the key problem with drawing that conclusion from that figure: while more Down pregnancies are being brought to term, there is another factor that needs to be taken into account in order to place that in its correct context:
There has indeed been a 4% increase in Down’s syndrome live births in England and Wales from 1989 to 2006 (717 and 749 affected births in the two years respectively). However, since 1989 there has also been a far greater increase in the number of Down syndrome foetuses created in the first place, because people are getting pregnant much later in life.
What causes Down syndrome? We don’t really know, but maternal age is the only well-recognised association. Your risk of a Down syndrome pregnancy below the age of 25 is about 1 in 1600. This rises to about 1 in 340 at 35, and 1 in 40 at the age of 43. In 1989 6% of pregnant women were over 35 years of age. By 2006 it was 15%.
I was not aware of the age-at-birth link to Down syndrome. (My mother was about to turn 44 when I was born. 1 in 40 might sound like long odds to you, but they're not long enough if you ask me...)
But what does this shift in birth patterns mean for claims of a more caring society?
The National Down Syndrome Cytogenetic Register holds probably the largest single dataset on Down syndrome, with over 17,000 anonymous records collected since 1989, and one of the most reliable resources in the search for patterns and possible causal factors. They have calculated that if you account for the increase in the age at which people are becoming pregnant, the number of Down’s Syndrome live births in the UK would have increased from 1989 to 2006: not by 4%, but from 717 to an estimated 1454, if screening and subsequent terminations had not been available.
Except, of course, antenatal screening is widely available, it is widely taken up, and contrary to what every newspaper told you this week, it is widely acted upon. More than 9 out of ten women who have an antenatal diagnosis of Down’s syndrome decide to have a termination of the pregnancy. This proportion has not changed since 1989. This is the “decisions” that Felicity Finch, Radio 4, the Mail, the Times, the Mirror, and the rest are claiming more parents are taking: to carry on with a Down syndrome pregnancy. This is what they are taking as evidence of a more caring society. But the figure has not changed.
While I'm interested in this story largely as a cautionary tale for the misuse of statistical data leading to the misunderstanding of society (which is a problem that is magnified in a historical context, when the statistics are a bit more iffy and our other information about social context more partial), Goldacre points out that there is a more direct reason why such stories are problematic.
Crass and insensitive moral reasoning helps nobody. If I terminate a Down syndrome pregnancy, is that proof that society is not a warm caring place, and that I am not a warm caring person? For many parents the decision to terminate will be a difficult and upsetting one, especially later in life, and stories like this make a pretty challenging backdrop for making it. This would have been true even if their figures had been correct, but as is so often the case, for those with spare flesh to wave at strangers, their facts and figures are simply incorrect.He also links to further background provided by the NHS, if you care to look.