Monday, January 10, 2011

Casual Links do Not Prove Causation

Talking with my sister this week, she made a comment that got me to thinking, and actually prompted me to caution her on the myriad of logical fallacies one commits when they assume that because A is true, and B is true, that A somehow causes or is tied to B. It isn’t always that clear cut, though, which is why I am writing this. My sister’s example:

She doesn’t drink soda (or pop, or coke, or whatever you call it regionally) because she cited a study that showed that people who drank soda were on average 10 pounds heavier than people that do not drink soda. Further comments by her lead me to believe that it was her understanding, based on the study, that if a person who does not drink soda started to drink soda, that they would gain, on average, about 10 pounds as a result of drinking soda. After all, doesn’t the study say exactly that?

Well, not really.

Here is why. There could be a myriad of other reasons why people who drink soda are heavier than those who don’t, and these reasons range from soda only being partially to blame, or not to blame at all. For instance, could it be possible that people who make a conscience decision eschew the consumption of soda could be less weighty simply because they, as a whole, make better dietary and health decisions in general, including but not limited to the decision to not drink soda? This decision is typically health based; soda is not good for you, so they decided to not drink it. But couldn’t this be true of other dietary intakes? If they are concerned with eating and drinking well, enough so that they eschew soda, isn’t it reasonable to think that they also make other good decisions like lowering calories and fat intake, reducing sodium, and eating less? Could the ten pound weight difference have little to do with soda, itself, and more to do with the lifestyle of people who decided to not drink soda? Could it be that a person making all of these other good dietary decisions, but still deciding to drink soda, might not gain a single pound?

I saw another study recently that caused me to pause, again. The study stated that children who watch more than 3 hours of TV per day do less well on standard tests than children who do not. Again, I wonder if the headline should have read “Children Who’s Parents Ignore Them for 3 Hours Per Day Do Less Well Than Children Who’s Parents Who Interact With Them, Find Other Activities For Them, and Do Not Ignore Them.”

Start listening to these studies, and pay attention to other possibilities that could be creating the result other than the stated, studied cause. I think you’ll find that there are at least a handful of other, logical reasons for the study’s results other than the concluded outcome given by the scientists, every single time. I remember an article I read last year that was an alarmist piece about melting glaciers that read something like “plants that have not been exposed for 5,000 years are being exposed as XXX Chilean Glacier melts away because of current warming.” I read it differently. I read it more along the lines of “5,000 years ago, the planet was warm enough that this glacier had receded so far that plant life lived here, in an area that is only just now being uncovered, meaning that it is still colder now than it was 5,000 years ago.” Yawn.

Keep an open mind. Think for yourself. Stay alert. Stay focused.

No comments:

Post a Comment