2.3 Supply Schedule, Function and Law

(A) Supply Schedule: Just as goods are demanded by consumers, they are supplied by manufacturers or sellers. At any point of time quantity supplied by them is a function of the market price. Several such prices can be related to the relevant quantities supplied: this would give the supply schedule. In the given schedule, as price of the goods rises (from zero to 3) the quantity supplied also rises (from zero to 6 units).

Supply Schedule
qs	P
0	0
2	1
4	2
6	3

(B) Supply Function: Supply is a direct function of the price and it rises or falls with the price. This is because the law of supply is based on the behavior of the cost of production. Assuming that manufacturers begin at the point where cost of production is minimal any further production and supply of goods can be possible only at an increasing additional or marginal cost per unit. Hence they can afford to supply more only at a rising price. Further, logically any seller would be willing to sell more goods if the price were to rise. The quantity supplied at the given range of prices as above can be presented in the form of an algebraic function:

q_s = 2P

With the help of the function we can find the quantity supplied at any randomly chosen prices. For instance, when P = 3, q_s = 6 or when P = 2, q_s = 4 etc.

(C) Law of Supply: The law of supply can be stated as follows:

"Ceteris paribus, the quantity of a good supplied will rise (expand) with every rise in its price and the quantity of a good supplied will fall (contract) with every fall in its price."

In a functional form this can be stated as :
q_s = f (P) [T, R, P] _const.

The quantity of a commodity supplied is thus a function of its own price. There exists a direct relationship between the quantity supplied and the price of a commodity. It is subject to the condition that other things should remain constant. In this case ‘other things’ include mainly two things. These are technical conditions or methods of production (T) and the prices and quantities of the resources supplied (RP). With improved technical conditions, supply can be increased at the same old price, since the cost of production can now be reduced. Similarly with an enhanced supply of resources and a reduction in the prices of resources such as land, labor, raw materials etc. an increasing quantity of the commodity can be supplied at a constant or even falling price.

Figure 4

Figure 4 is the graphical representation (the supply curve) of the supply schedule. It begins at the point of origin where both quantity supplied and price are zero in value, and then it continuously rises upwards. This upward sloping curve indicates the positive relationship between supply and price: there is a rise in the quantity supplied with every successive rise in the price.

(D) Expansion or contraction and increase or decrease: Changes in the quantity supplied as a result of movement along the same supply curve has been described by Marshall as rise and fall or expansion and contraction of quantity supplied of the commodity. But if the supply curve shifts left or right of the original curve, the changes in supply of the good are known as increase or decrease.

Figure 5

In figure 5 we notice such a shift in the supply curve. On the original supply curve (OS) the quantity of goods supplied at price OP is Oq but when the supply curve shifts towards its left (i.e. S₁ S₁) then at the same price OP, the quantity supplied decreases to Oq₁. If we begin with S₁ S₁ as the original supply curve, OS would represent a shift of the supply curve towards the right. In this case, quantity supplied increases at a given price.

The supply curve undergoes a shift in it with a change in the technical conditions or the price and supply conditions of the inputs (resources). With improved techniques or methods of production, the degree of the efficiency with which some or all resources can be utilized will increase. This results in a favorable change in the cost of production. Similarly with improved supplies and reduced prices of the inputs, the cost of production tends to fall and an increased supply of a commodity becomes possible at a given market price.