The Skeptical Teacher

Musings of a science teacher & skeptic in an age of woo.

Posts Tagged ‘coincidence’

Prayer, Miracles, and Damned Statistics

Posted by mattusmaximus on April 7, 2010

We’ve all heard the line: There’s lies, damned lies, and then there’s statistics. The implication is that people can use statistics to deceive themselves and others.  But the opposite is also true: people often deceive themselves due to a stark ignorance of numbers & statistics (often referred to as innumeracy).

For example, at this time of year, at least in Christian circles, there is a lot of talk going around about prayer and miracles – usually in the guise of stories about supposedly “miraculous” healing.  And the media loves to give air time to these kind of anecdotal stories with nary a whiff of skepticism.  However, to its credit, ABC News did a segment recently with Elizabeth Vargas where she gave a fair amount of face-time to skeptic Michael Shermer.  Here are some excerpts from Shermer’s account of the interview at the really groovy SkeptiBlog…

Would I Ever Pray for a Miracle?

I really like how Shermer goes into the issue of large number statistics, confirmation bias, and believers counting the “miraculous hits” while discounting the enormous number of inevitable misses…

Read the rest of this entry »

Posted in mathematics, religion | Tagged: , , , , , , , , , , , , , , , , , , , , , , , , , | 2 Comments »

Wisdom in a Cookie

Posted by mattusmaximus on January 19, 2009

My wife and I love Chinese food.  Often, after a long day, I like to drop by our favorite Chinese restaurant and pick up some dinner.  And I think it’s hard to find many things better than a good, relaxing meal at the end of the day – unless, of course, you’re talking about dessert.  And what is the classic dessert of such fare?  The fortune cookie…

fortune cookie

Just today, we had some Chinese take-out, and I chomped a fortune cookie for dessert. Now, while I’m not going to claim that anyone really takes these kind of fortunes seriously, I’m going to use them as a little lesson in critical thinking because there are related phenomena that some people do take seriously.

Let’s take that fortune revealed in my cookie:

A party with friends is in your near future

Now, it is true that there are a few events in the upcoming weeks where I’ll likely be getting together with friends. So should I conclude that this little cookie successfully predicted the future? Of course not!

Were I to conclude this party prediction a “hit”, I would be guilty of a common logical fallacy, namely observational selection (also known as “cherry-picking” or “counting the hits but discounting the misses”). Observational selection is a common fallacy employed by those who believe the messages of psychics – like Sylvia Browne or Nostradamus – can accurately predict the future.

Think about it, of all the people who receive fortune cookies every day, probably many people got the same message about an upcoming party with friends. Chances are, most were not going to have such a party (a “miss”), and those people would basically ignore the miss and just eat the cookie. But then I get this cookie which seems to successfully predict an upcoming gathering of friends (a “hit”?). You can see what’s going on here – it’s just basic statistics. Many more “party with friends” cookie predictions miss than hit, but those are ignored in favor of the hits.

With a psychic’s predictions, such as Ms. Browne’s predictions for 2008, as with a fortune cookie, most of the predictions fall flat as misses. Actually, to be fair to Browne, she got half of the predictions listed at that link correct, but many were extremely vague predictions that I think hardly count (when do we go through a year with no earthquakes?). But the true believers ignore these misses, and then they employ selective thinking to justify whatever hits they perceive of “proof” of the psychic’s powers.

Side note: If Sylvia Browne (or any other psychics) really had any powers she claims to have, you might think that she would have predicted the global economic meltdown. Funny that she didn’t, isn’t it? I mean, it was only the biggest financial crisis in the world since the Great Depression…

Oops, that’s a pretty BIG miss!!!

Now, can a fortune cookie (or psychic) get lucky, providing a “prediction” of a once-in-a-million hit? Certainly, it can happen. For example, here’s a story about a “fortune-cookie-payout” where many people won millions of dollars based upon the numbers on a fortune cookie…

Powerball officials initially suspected fraud, but it turned out that all the winners received their numbers from fortune cookies made by Wonton Food Inc., a fortune cookie factory in Long Island City, Queens, New York. The number combinations printed on fortunes are reused in thousands of cookies per day. The five winning numbers were 22, 28, 32, 33, and 39. The sixth number in the fortune, 40, did not match the Powerball number, 42.

Were those people just lucky or was there something psychic at work with the fortune cookies? The discussion about statistics above should give you a hint, and besides, there’s a reason why it’s a called once-in-a-million shot. With enough cookies handed out over enough years, and with enough people playing lottery numbers based on those fortunes, eventually someone will get lucky.

So where’s this “wisdom” I mentioned in the title of this entry? Well, dear reader, I think the wisdom given to us by those tasty little fortune cookies is a lesson in critical thinking – how not to be fooled and, more importantly, how not to fool ourselves.

Posted in psychics | Tagged: , , , , , , , , , , , , , , , , | 8 Comments »

 
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