Anyone who attended Strathroy District Collegiate Institute in the 1990′s (such majesty) and took OAC Economics with Mr. Hughes will recognize the title. I think he used to say it at least once every class.
I mean, bless him for it because it stuck with me and I remind myself of it all the time. It’s the first thing I thought of when I saw this graph (via Megan McArdle):
Three cheers for Mexican lemons saving lives on US highways!!!
Everyone who ever took a class on statistics has learned that correlation does not imply causation. But we see people making these claims all the time — in politics and business especially — in situations where people need some basis for making a decision and don’t have the luxury of more time for data-gathering and factoring-in of other variables.
Or… concerning issues that have emotional resonance. As David Hume famously said, reason is “slave of the passions.” We tend to make up our mind first and then grab whatever numbers or pseudo-rational explanations we can whip together. [Check out psychologist Jonathan Haidt for more current research.]
For example, um, the alleged link between autism and vaccine – which isn’t even correlative but nevertheless generated a vocal social movement. (But with the vaccine ruled out, hey maybe there’s a link between autism and vinyl floors…)
More controversially, what about climate change?
On the subject, I highly recommend this profile of Freeman Dyson in the New York Times last week, “The Civil Heretic.” The eminent physicist has been the target of ill-regard for his thinking about climate. Dyson’s attitude is that we (or at least some people) ought to be skeptical of the growing model-based, mass-movement consensus about man-made global warming.
I honestly don’t know what I think. I’m of the opinion that reducing pollution is a good enough purpose without all the hubris about saving the planet (which got along pretty well without us — or not — for quite some time), and I’m worried that if we invest too much faith in our ability to control the climate, we’ll be driven mad by inevitable random fluctuations and long-term trends that may-or-may-not have been caused by us.
[Then again, the climate change cause is a fabulous motivator to concentrate and amplify our efforts to clean up our collective act... Like I said, I honestly don't know -- but whatever works is ok by me.]
One thing I know for sure (in light of the collapse of the model-driven quantitative finance): don’t always trust the prettiest graph.
