1. Definition
   1. Measures Nature and Degree of
      1. Changes in quantity of food demanded
      2. Changes in income
2. Floating Topic
   1. Y = income
   2. Q = Quantity
3. Degree of relationahip
   1. The nature of the relationship is revealed by the Sign
   2. 0
      1. perfectly inelastic
   3. <1
      1. inelastic
         1. Change in demand is less then change in price
   4. 1
      1. unit elastic
         1. giffen good
            1. change in demand = change in price
         2. normal good
            1. luxury
   5. >1
      1. elastic
         1. change in demand is greater then change in price
   6. ∞
      1. perfectly elastic
4. Nature of relationship
   1. Positive
      1. Variables move in the same direction
   2. Negative
      1. move in opposite directions