Whenever I see correlation confused with causation, it reminds me of a time in my early teens when the A&P (Agricultural and Pastoral) show was in my home town. People started getting sick, and the common factor seemed to be attendance at the A&P show. Suspicion started to fall on those providing food at the A&P show, particularly for some reason on the hot dog vendors.
A few days later, the cause of the illness was shown to be norovirus, but not before some rather nasty things had been said about the food vendors. As norovirus is highly contagious, it is more than likely that the close proximity of people at the A&P was more than enough to allow rapid spread of the norovirus. So while there was a correlation between those attending the A&P show, and those get sick, the hot dog vendors were unlikely to be the causation.
This event taught me two things – first, that when it comes to health, we are generally very conservative and cautious. Secondly, and less flatteringly, it taught me how susceptible we can be to scapegoating and behaving out of fear and ignorance.
Our history is littered with examples of scapegoating, for example – disease being blamed on the work of the witches, resulting in the deaths of innocent local women. And this carries through to the modern day where people still die in “exorcisms”.
During the emerging AIDS crisis of the 80’s and 90’s – most New Zealanders will probably remember the name of Eve van Grafhorst, the Australian pre-schooler who was hounded out of her local pre-school in Kincumber, New South Wales, with some in the community even suggesting that the family leave town (which they eventually did, moving to New Zealand where she was able to attend school with relatively few hassles).
Examples of confusion between correlation and causation are apparent in the anti-vaccine movement today. Most children receive vaccines at around the same time as the first indicators of autism start to become obvious. Consequently while the correlation between vaccines and the development of autism is a temporal one – they tend to occur around the same time, it does not follow that the vaccines are causing autism.
We are extremely cautious when it comes to looking after our health, an approach that in terms of the survival of our species has served us quite well. However, as we grow more knowledgeable we need to learn to balance this precautionary instinct with greater rationality and empathy for those around us.