When I was a kid, we couldn't have a nightlights because they had discovered a correlation between kids who have nightlights and bad vision. They looked at the data carefully, and there was definitely a relationship between nightlights and vision--not at all a coincidence.
But then along came a better statistician, who understood what a confounder is--the third wheel that can change a suspected causation into merely a correlation.
The confounder in this case was the parent's vision. If they needed to wear glasses, then they tended to put nightlights in their children's room, because they'll often check their children at night, when they aren't wearing their glasses. And your focus is better when there is light.
And if parents have bad vision, then their kids are more likely to have bad vision. So nightlights had nothing to do with causing bad vision in kids.
It's funny but it's also surprisingly true. The brighter light closes your iris which helps your eyes focus.
ReplyDeleteWell, knock me over with a feather.
ReplyDeleteIt brings up the old statistics lesson.
ReplyDeleteWhen I was a kid, we couldn't have a nightlights because they had discovered a correlation between kids who have nightlights and bad vision. They looked at the data carefully, and there was definitely a relationship between nightlights and vision--not at all a coincidence.
But then along came a better statistician, who understood what a confounder is--the third wheel that can change a suspected causation into merely a correlation.
The confounder in this case was the parent's vision. If they needed to wear glasses, then they tended to put nightlights in their children's room, because they'll often check their children at night, when they aren't wearing their glasses. And your focus is better when there is light.
And if parents have bad vision, then their kids are more likely to have bad vision. So nightlights had nothing to do with causing bad vision in kids.