Gambler’s Fallacy?

Written by Tad. Posted in Kooks

My wife, Shari, forwarded me a link to a segment on NPR about Gambler’s Fallacy. In short, Gambler’s Fallacy refers to our brain’s tendency to see patterns in random events then thinking those patterns can predict future events.

A simple example is a gambler betting on whether a flipped coin turns up “heads.” Each coin flip has a 50:50 chance of resulting in “heads.” If, in a series of flips, “heads” come up several times in a row, the gambler thinks the next one just has to be “tails,” even though heads is still a 50:50 chance in each flip. The gambler puts all his money on “tails” since, after so many “heads” in a row, the next throw just has to be “tails.” He looses his money when “heads” comes up again.

An interesting example of the Gambler’s Fallacy played itself out in our emergency department last week.

I was seeing a 9-year-old girl who had abdominal pain for three days. From her examination and laboratory tests, it looked for all the world like she had appendicitis. Coincidentally, her 12-year old sister had just had her appendix taken out that day in our hospital.

My patient got sick the day after her sister. Her family had just kind of ignored her complaints because she had not seemed very ill and everyone’s attention was drawn to the sister who had been admitted to the hospital for surgery.

Eventually, Mom and Dad brought her to the emergency department wondering if she might also have appendicitis. Everyone taking care of her saw that she had the symptoms of appendicitis and that her abdomen was tender like you would expect in someone with appendicitis. But no one was willing to take her to the operating room and cut out her appendix because her sister had just had the same operation. It was such a big coincidence that it made everyone uncomfortable.

Still, the 9-year-old was too ill to send home, so she was admitted to the hospital for observation. The next day, it was clear she needed an operation. Operate they did and, sure enough, found her to have appendicitis.

So, two sisters both came down with appendicitis within a day or two of each other and both had an operation and were in the hospital at the same time.

Here is the link to the NPR story on Gambler’s Fallacy:


Trackback from your site.

Comments (1)

  • Marlene


    The poor younger sister had to be in pain for a longer period of time because of a coincidence it would be for two sisters to have the same thing. But glad she finally got some relief.


Leave a comment

Copyright © 2014 Bad Tad, MD