Investors, page-11

Neither is tomorrow share price,
interest rate on corporate debt issue (until it is issued)
the recovery rate of oil from a well
the production rate of the well tomorrow, next week, next month,
the reservoir properties until the well produces
the price of oil in the next hour
do I need to go on.

The point is all variables have some form of "Expected" unless you its past tense where it has become a measured quantity. The world of finance is full of Expected numbers and Required numbers (as in I need this required return to make the investment and for that to happen I need ....)

As far a risk goes, that is somewhat easier and you will often hear things like Market Risk and those have been measured of the years and years and years of stock market data to get equity risk - commonly referred to as its beta!

Rational or Irrational - which one?