

Apple is so big that analysts are stripping it from the S&P 500 - BenS
http://finance.yahoo.com/news/apple-s-size-clouds-market.html

======
jacques_chester
This is another example of how a raw arithmetic mean can be highly deceptive.
Looking at the median performance, or the mean +/- standard deviation, is much
more informative.

A good example (which I picked up from _Gnuplot in Action_ ) is this: you're
organising a marathon and need to know when to have end-of-race refreshments
ready. You load end time records into a database, then take an average (say
... 1 hour, 30 minutes). You plan to put out drinks at 1 hour 15 minutes,
expecting the bulk of the runners to arrive then.

The big day arrives. Suddenly, around the 50 minute mark, runners start
arriving in surprisingly large quantities. It's a disaster, there's nothing
for them to drink, and afterwards you live a life of chagrin and go to your
grave humiliated (marathon runners are pretty serious people).

What the mean obscured was that the marathon times were bimodally distributed.
About 20% of runners, serious marathoners, arrived "early", and the rest of
the runners much later. If you'd thrown it up on a graph or looked at some
other figures, you'd have known. But you were deceived by the easiness of the
mean.

