Law of Demand:

 

     There is an inverse relationship between relative price and the quantity demanded, other things equal (ceteris paribus).  In other words, a “downward sloping demand curve.”

 

Reasons for the Law of Demand:

 

     Substitution Effect: The tendency for people to substitute in favor of cheaper goods and away from more expensive ones is the substitution effect.

 

     Real-Income Effect: The change in people’s purchasing power when the price of one of the goods they buy changes is the real-income effect.