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Conference rusure::math

Title:Mathematics at DEC
Moderator:RUSURE::EDP
Created:Mon Feb 03 1986
Last Modified:Fri Jun 06 1997
Last Successful Update:Fri Jun 06 1997
Number of topics:2083
Total number of notes:14613

711.0. "Coincidence" by IECG::GREENWOOD (Tim - International Engineering) Tue Jun 02 1987 21:55

   (Posted to MATH and ASKENET)
     
    Wild coincidences seem to occur more often that 'common sense'
    indicates that they should. For example:
      
    At a show in Disneyworld we discover that the people at the next
    table live in the house that we lived in (in Mass). We had not met
    them before. Two months later one of them starts work at DEC in
    the next office to me.
    
    While walking through Muir woods near San Francisco we meet a
    friend from DEC Germany.
    
    (When we lived in England). On visiting the National Theatre in
    London we are sat in front of couple that we met the previous week
    on vacation in Italy.
    
    A couple of weeks later we run into another couple from the same
    vacation (who did not live in the same town as us, but from the
    general wider area).
    
    etc.
    
   Do other people run into the same sort of coincidences ?
   Are they in fact such wild coincidences? If you run the probability
   numbers would you expect some of these 'wild coincidences' every few
   years ?
   
Tim
T.RTitleUserPersonal
Name
DateLines
711.1Yes, they happen to us all.AKQJ10::YARBROUGHWhy is computing so labor intensive?Wed Jun 03 1987 13:2721
The existence of such apparently wild events is the basis for a lot of 
belief in ESP, etc. and has been the target of a substantial amount of 
analysis. The magazine, "The Skeptical Inquirer", which has been mentioned 
in Scientific American and other places, has dealt with this issue.

I have observed that about every 4th or 5th time I go to any airport, I run
into someone whom I know but didn't expect to see. It's especially true of
Logan, but I have run into a friend from Philadelphia in a Chicago airport, 
when I was on a trip from LA, etc. This doesn't count TV stars and other
highly visible people whom I recognize but don't know, and who seem to
frequent airports as often as taxi drivers do. 

I think I know exactly one (1) Naval officer. It turns out he is the 
Captain of the USS Stark, which is in the news a lot this week.

The thing that is scary about such events is that we NOTICE them, in 
preference to the tens of thousands of non-eventful things that happen 
every day. Since our attention is drawn to them, they seem more frequent 
than they really are.

Lynn Yarbrough 
711.2I agree with .1EAGLE1::BESTR D Best, Systems architecture, I/OWed Jun 03 1987 20:0623
  I agree with .1.  Coincidences are simply events that have some
particular significance to us and are primarily a result of selective
perception.

  You may have heard of the 'poker hand' experiment that's designed to
convince people of the power of selective perception.

  The experiment is this:  If you play poker (an analogous thing can be
done with bridge), deal yourself a hand and record the suit and rank of
each card in the hand.  Every time you play, watch for an occurrence of that
particular hand.  Chances are good that you'll never see that hand again.

  The point is that each hand is a low probability event.  That is, the
a priori probability of drawing that particular hand is the same as
every other hand.  Because we distinguish certain hands as 'special' (e.g.
a royal flush in hearts), there is a psychological tendency to feel
that the 'special' hand is particularly surprising.

  I don't find people coincidences too surprising given the fact that
most people I know are quite similar to me.  We therefore have a tendency to
travel in similar circles and do similar things (e.g. going to Disneyworld;
just about everybody I know has been to Disneyworld in the last four or five
years).
711.3Fancy not meeting you here!KIRK::KOLKERWed Jun 03 1987 21:215
    Think about all those unfortunate blokes who don't run into ex
    neighbors will hiking thru East Armpit, etc, etc.. These non
    coincidences balance out the coincidences and overall you get about
    what probabilities dictate.
    a
711.4You are statisticsTAV02::NITSANDuvdevani, DEC IsraelThu Jun 11 1987 08:438
Re.1:

I agree completely, but I read one more "strange" explanation:

If (say) you let one guy guess a sequence of cards given to another (as done
in ESP tests) probability predicts the expected number of correct guesses. The
same probability theory says that if you do the whole test many times on many
people - in SOME cases you should get results better than the expected...