In economics, supply and demand together determine the price and quantity of goods and services in a market. It is very important to clearly understand the difference between a movement along a curve and a shift of a curve. A shift in supply or demand means a change in the entire relationship between price and quantity, caused by factors other than the price of the commodity itself.
A shift occurs when there is a change in the quantity demanded or supplied at the same price level due to changes in non-price factors. When demand or supply shifts, the whole curve moves either to the right or to the left, leading to changes in both equilibrium price and equilibrium quantity.
Effect of a Shift in Demand
A shift in demand takes place when consumers are willing to buy more or less of a commodity at the same price due to changes in factors such as income, tastes, population, prices of related goods, or expectations about the future. This shift can be either an increase in demand or a decrease in demand.
When there is an increase in demand, the demand curve shifts to the right. This means that at every price level, consumers demand a larger quantity than before. Such a situation may arise due to an increase in consumer income (in case of normal goods), growth in population, rise in prices of substitute goods, fall in prices of complementary goods, or a favourable change in consumer tastes. As demand increases while supply remains constant, excess demand is created in the market at the existing price. Producers respond to this excess demand by raising prices, which results in a new equilibrium with a higher price and larger quantity.
On the other hand, a decrease in demand leads to a leftward shift of the demand curve. In this case, consumers demand less at every price level. This can happen due to a fall in income, decline in population, unfavourable changes in taste, fall in prices of substitutes, rise in prices of complementary goods, or pessimistic expectations about future income or prices. With supply unchanged, excess supply appears at the existing price, forcing sellers to reduce prices. The market then reaches a new equilibrium at a lower price and smaller quantity.
It is important to remember that a shift in demand changes both price and quantity, whereas a movement along the demand curve changes only quantity due to a change in price.
Effect of a Shift in Supply
A shift in supply occurs when producers are willing to supply more or less of a commodity at the same price because of changes in factors such as input costs, technology, taxes, subsidies, or number of producers. Like demand, supply can also shift either to the right or to the left.
An increase in supply is represented by a rightward shift of the supply curve. This means that producers supply a larger quantity at every price level. This may be due to improvement in technology, fall in cost of production, reduction in taxes, increase in subsidies, or entry of new firms into the market. When supply increases while demand remains unchanged, excess supply emerges at the existing price. To clear this excess supply, sellers reduce prices, resulting in a new equilibrium with a lower price and higher quantity.
A decrease in supply causes a leftward shift of the supply curve. In this situation, producers supply less at every price level due to factors such as rise in input costs, outdated technology, increase in taxes, reduction in subsidies, or exit of firms from the market. With demand remaining constant, excess demand is created at the old price, pushing prices upward. The market settles at a new equilibrium with a higher price and lower quantity.
Combined Shifts in Demand and Supply
In many real-life situations, both demand and supply may change at the same time. The final effect on price and quantity depends on the direction and magnitude of these shifts. If both demand and supply increase, the equilibrium quantity will definitely increase, but the effect on price will depend on whether demand or supply increases more. Similarly, if both decrease, equilibrium quantity will fall, but the price effect will depend on the relative strength of each shift.
If demand increases while supply decreases, both factors push the price upward, resulting in a sharp increase in price, while the effect on quantity is uncertain. Conversely, if demand decreases and supply increases, prices will fall significantly, while the effect on quantity depends on the extent of the shifts.
Importance of Shifts in Supply and Demand
Understanding shifts in supply and demand is crucial for analysing market dynamics, inflationary pressures, shortages, and surpluses in the economy. For bankers and finance professionals, these concepts help in assessing market conditions, credit demand, pricing of financial products, and impact of policy decisions such as tax changes or subsidies.
In banking terms, for example, an increase in demand for housing combined with limited supply can push up property prices, affecting loan size and credit risk. Similarly, a technological improvement in production can increase supply and reduce prices, influencing working capital requirements.