Introducing Supply and Demand

Read the sections on Demand, Supply, Market Equilibrium, and Government Intervention and Disequilibrium for a mathematical exposition of the demand and supply model, clicking through to the next when you have finished each page. The chapter also covers price ceilings and price floor analysis as well as quantity regulations.

Supply Schedules and Supply Curves

A supply schedule is a tabular depiction of the relationship between price and quantity supplied, represented graphically as a supply curve.


Explain the price to quantity relationship exhibited in the supply curve


Key Points
  • The supply curve plots the quantity that is willingly supplied at any given price.
  • The individual supply curves can be summed by quantity provided at a specific price to achieve an aggregate supply curve.
  • The supply curve is upward sloping in the short run.

Key Terms
  • aggregate: A mass, assemblage, or sum of particulars; something consisting of elements but considered as a whole.
  • equilibrium: The condition of a system in which competing influences are balanced, resulting in no net change.

Supply is the amount of some product that producers are willing and able to sell at a given price, all other factors being held constant. In general, supply depicts a positive relationship between the price of a good or service and the quantity that the producer is willing to supply: if a supplier believes it can sell the product for more, it will want to make more of the product. As a result, as the price of a good or service increases, suppliers increase the quantity available for purchase.

A supply schedule is a table that shows the relationship between the price of a good and the quantity supplied. The supply curve is a graphical depiction of the supply schedule that illustrates that relationship between the price of a good and the quantity supplied.

The Supply Schedule and Supply Curve: The supply curve is a graphical depiction of the price to quantity pairings presented in a supply schedule. The supply schedule is a table view of the relationship between the price suppliers are willing to sell a specific quantity of a good or service.

The supply curves of individual suppliers can be summed to determine aggregate supply. One can use the supply schedule to do this: for a given price, find the corresponding quantity supplied for each individual supply schedule and then sum these quantities to provide a group or aggregate supply. Plotting the summation of individual quantities per each price will produce an aggregate supply curve.

In theory, in the long run the aggregate supply curve will not be upward sloping but will instead be vertical, consistent with a fixed supply level. This is due to the underlying assumption that in the long run, supply of a good only depends on the fixed level of capital, technology, and natural resources available.

The supply curve provides one side of the price-to-quantity relationship that ensures a functional market. The other component is demand. When the supply and demand curves are graphed together they will intersect at a point that represents the market equilibrium – the point where supply equals demand and the market clears.