The "what the heck" or "the costs are so small" are common reactions to trying out any number of dubious strategies for improving health. I teach a first year seminar class called "Why do people believe weird things" and even at the end of the semester after we have talked at length about the cognitive and motivational factors for why people believe a host of different weird things (we mostly focus on paranormal events not on health) many students still say: sure I would try a dubious strategy just in case it worked for me (they don't remember the problem of placebos).
My point to them is that trying anything (even if there are few apparent costs) is costly because it means that we did not try something else that might have been effective. We can probably only undertake a finite number of activities to improve our health (emotionally, financially, time wise, etc.) so each method undertaking takes up space and probably squeezes out another (more effective) method that we therefore did not try (e.g., we should put all our efforts into quitting smoking - a difficult task that give you huge health benefits - over taking a spoonful of soy a day or losing a few pounds). The other point I make is that actions that seem to have low cost today could have unanticipated bigger costs later (because of habits, belief perseverance and placebo effects). So parents of autistic kids who tried facilitated communication (it might work, seemed low cost) could not have anticipated the huge costs later (as schools adopted a worthless technique, court cases of abuse abounded, etc.). So one should probably be pretty careful before adopting dubious methods even if they seem to be of low cost. Marie **************************************************** Marie Helweg-Larsen, Ph.D. Department Chair and Associate Professor of Psychology Kaufman 168, Dickinson College Carlisle, PA 17013, office (717) 245-1562, fax (717) 245-1971 http://www.dickinson.edu/departments/psych/helwegm Office hours: Monday 10:30-11:30, Tuesday & Wednesday 2:00-3:30 **************************************************** From: Michael Smith [mailto:[email protected]] Sent: Tuesday, April 14, 2009 11:05 PM To: Teaching in the Psychological Sciences (TIPS) Subject: Re: [tips] [Bowel cancer risk in older women could be reduced by more soya in diet | Science | The Guardian] Thank you all for the clarifications. Yes, I was going more along the lines of 7-2=5; 2 saved. And yes, I agree the 30% is misleading. And no I won't take the bet on cell phones; I believe you (Chris) are right. The only trouble is, that the cell-phone user will be the only uninjured party in the accident (again no data)! The question was intended to reflect more of the "If I'm a woman and I have to eat a teaspoon of soy once a week, what the heck", even if the effect was very small since I don't think there are any risk factors for soy consumption (unless maybe you eat tons of it, then there is no doubt risk as with probably everything--including water). Of course, as Chris said the actual consumption wasn't reported, but I thought a teaspoon to be reasonable since I didn't believe hardly anyone in the UK would eat soy products; but times are changing I guess. I look at the reaction to these kinds of things (as my question was intended to reflect) as a type of lottery thinking. I may know that my chances of winning the lottery are 1 in 60 million, but it still doesn't stop me buying the ticket, because the cost is so little and the payoff so big. (I am using "I" and "me" in the universal sense, since of course "I" would never fall prey to any of this). --Mike On Tue, Apr 14, 2009 at 8:13 PM, Shearon, Tim <[email protected]<mailto:[email protected]>> wrote: Brandon and Chris both made good points. Another way to look at this is to note that the question, "What if you are one of the two?" has an implied sense that if you were tested you'd be identified and therefore saved- 7 - 2 = 5. But that assumes that "the two" who are going to die of the disease would be "caught" by the testing. Clearly not so. "What if you were one of the 5?" is a more telling question. Clearly being tested isn't going to help them. And there is no way to know prior to testing that the 5 are the 7 minus the two, as it were. The statistics, as Chris' analysis has shown for several of these examples of causal confusion, don't work that way. Tim _______________________________ Timothy O. Shearon, PhD Professor and Chair Department of Psychology The College of Idaho Caldwell, ID 83605 email: [email protected]<mailto:[email protected]> teaching: intro to neuropsychology; psychopharmacology; general; history and systems "You can't teach an old dogma new tricks." Dorothy Parker -----Original Message----- From: Christopher D. Green [mailto:[email protected]<mailto:[email protected]>] Sent: Tue 4/14/2009 7:41 PM To: Teaching in the Psychological Sciences (TIPS) Subject: [tips] [Bowel cancer risk in older women could be reduced by more soya in diet | Science | The Guardian] Michael Smith wrote: > > Hmmm. > But what if you are one of those two? Then you die (by definition). The problem is you don't know you are one of those 2 until you are dead. We have to make these decision on the basis of the probabilities well ahead of time. There are lots of things that raise our chance of death by a lot more than 2 in 10,000, and we should worry about them first. Smoking in #1. Smoking raises the chances of a 65 year old man dying of lung cancer in the following 10 years from 4 in 1000 to 89 in 1000. Now there's some action. This 2 in 10,000 stuff is mere peanuts in comparison. I don't have then numbers, but I'll bet you $5 that talking on a cell phone while driving increases the probability of having a car accident by a lot more than 2 in 10,000. (According to some research, talking on a cell phone makes the driver as impaired as drinking over the .08 level.) Chris Green York U. Toronto ============= > > > On Sun, Apr 12, 2009 at 10:31 PM, Christopher D. Green > <[email protected]<mailto:[email protected]> > <mailto:[email protected]<mailto:[email protected]>>> wrote: > > > Here's another example of misleading medical statistics example > you might want to use in class. > http://www.guardian.co.uk/science/2009/apr/11/bowel-cancer-soya > > The report says that more soy in the diet (it doesn't say how much > more) can reduce women's chance of death from bowel cancer by 30%. > (Actually, it says those in the top third of soya intake had a 30% > decrease in bowel cancer deaths, compared to the bottom third -- > NOTE: not from the national average -- but it doesn't give any > indication of how much soy each group actually ate.) > > So let's work the numbers. 16,600 women die from bowel cancer per > year in the UK. There are about 60 million people in the UK. Half > are female: 30 million. Lose the 20% children and we have 24 > million women. > > So, the chance of dying of bowel cancers for women in any one year > is: > 16,600/30 million = .0007, or 7 in 10,000. > > A 30% reduction would lower that chance to 5 in 10,000. > > So (even if the causal implication that is not actually > demonstrated here were correct), if increasing your soy intake by > a fair bit could decrease your chances of dying by bowel cancer by > 30%, that would represent a tiny reduction of just 2 in 10,000 per > year. > > > Chris > -- > > Christopher D. Green > Department of Psychology > York University > Toronto, ON M3J 1P3 > Canada > > > > 416-736-2100 ex. 66164 > [email protected]<mailto:[email protected]> > <mailto:[email protected]<mailto:[email protected]>> > http://www.yorku.ca/christo/ > > ========================== > --- To make changes to your subscription contact: Bill Southerly ([email protected]<mailto:[email protected]>) --- To make changes to your subscription contact: Bill Southerly ([email protected]<mailto:[email protected]>) --- To make changes to your subscription contact: Bill Southerly ([email protected]) --- To make changes to your subscription contact: Bill Southerly ([email protected])
