1. Formula
   1. P1
      1. original price
   2. P2
      1. New Price
   3. Q1
      1. Original quantity supplied
   4. Q2
      1. New quantity supplied
2. 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
3. Nature of relationship
   1. Positive
      1. Variables move in the same direction
   2. Negative
      1. move in opposite directions