Final answer:
Elasticity of supply allows us to compare the responsiveness of the quantity supplied to price changes across different goods or when measured in different units, as it is a percentage change that is independent of measurement units.
Step-by-step explanation:
The elasticity of supply is a units-free measure of responsiveness of the quantity supplied of a good or service to a change in its price. Because elasticity is calculated as the percentage change in quantity supplied divided by the percentage change in price,
we can make comparisons between the responsiveness of the same good when quantity is measured in different units, or we can compare the responsiveness across different goods. This is because elasticity is not dependent on the units in which the variable is measured, making it a very useful tool in economic analysis.
It is important to note that elasticity is not the same as the slope of the demand or supply curve. Unlike the slope which is the rate of change in units along the curve (rise over run), elasticity is concerned with the percentage change, indicating how responsive the quantity demanded or supplied is to a price change.
Therefore, the price elasticity changes along the curve even though the slope may remain constant.