Quantum physicists talk about the "observer effect". At the sub-
atomic level, the very act of observation affects the results of
experiments. It is impossible for example, to directly observe a
photon without destroying it. IT specialists also refer to a
more commonly understood version of the observer effect. When a
program is run to test the speed of a PC, the program itself may
use resources that slow down the PC. Investors and traders run
into their own version of such effects sometimes when they try
to act upon an observed trend. Their actions and observations
can change the way the market operates. If somebody tries an
investment strategy and it works, it is then imitated by others.
If a large number of people follow the strategy, it reduces the
effectiveness and the expected returns. For example, during the
Depression Era (1929-1937), Benjamin Graham was highly
successful buying profitable businesses trading at below book-
value. Then Graham explained his seminal ideas. Other investors
became aware of h