Biology News Net reports that a Canadian study shows bilingualism has protective effect in delaying onset of dementia by four years. It's total nonsense, of course, ... but what the heck, it makes good press, n'est-ce pas?
I'm embarrassed that so-called scientists at my university are allowing such rubbish to be published in a press release. The clear implication is that there's something about speaking two languages that delays the onset of dementia and Alzheimer's. Correlation is not the same as cause and effect. Repeat after me, a correlation does not necessarily identify a cause.
Update: Here's the original press release from the Baycrest Centre.
The first thing that springs to mind when I see these sorts of studies is: how many other factors did they test, to see if they could find a correlation? (Probably several.) And did they draw their conclusions from the same data set which they probed for all these factors? (Probably yes.) If so, there isn't even any meaningful demonstration of correlation, let alone causation.
ReplyDeletePlay around with any data set and you will find some correlations somewhere. A correlation is only meaningful if you drew up your hypothesis before examining the data.
It's a beginner's blunder, but it gets repeated over and over and over again.