在经济学里，不仅有沉没成本，更有机会成本。
Quote:
Sunk costs are costs that have already been incurred and which cannot be recovered to any significant degree.
Opportunity cost" of any good or service is the value of all the other goods or services that we must give up in order to produce it。
因此，在Business decison making里，Sunk cost并不可以记入任何的成本中，而机会成本却是所有decision variable 中要考虑的关键，因为我们只可根据今天的情况和预期做出决定。
