Final answer:
The elasticity of demand differs even with consistent price and quantity changes due to factors like income levels, consumer preferences, time periods, and the price of related goods, which affect how demand responds to price changes. Elasticity varies in the short and long run, and it can be measured for different determinants of demand and supply.
Step-by-step explanation:
The elasticity of demand can differ even when the change in quantity and the change in price are consistent because elasticity measures how much the quantity demanded responds to a price change, which can be influenced by various factors other than price. These factors include income levels, consumer preferences, the price of related goods, and others. For example, if a good is a luxury, a rise in income levels might increase demand for it more than for a necessity, leading to a higher income elasticity of demand. Similarly, changes in consumer preferences can make the demand for a product more or less sensitive to price changes, affecting its price elasticity.
Elasticity also varies over different time periods. In the short run, supply and demand may be less elastic because consumers and producers need time to adjust to price changes. However, in the long run, they are more elastic because there is more time to make adjustments, resulting in more muted price movements and more substantial quantity adjustments. Elasticity can be measured not just for the price but also for any determinant of quantity supplied and quantity demanded, such as income or the prices of related goods, as the elasticity concept applies to the responsiveness of quantity supplied and demanded to changes in these variables as well.