How do we measure the three cases of demand elasticity?

Demand elasticity is measured through three main cases: price elasticity of demand, income elasticity of demand, and cross-price elasticity of demand. Price elasticity assesses how quantity demanded changes in response to price changes, calculated as the percentage change in quantity demanded divided by the percentage change in price. Income elasticity measures how quantity demanded responds to changes in consumer income, while cross-price elasticity evaluates the demand response for one good when the price of another good changes. Each type provides insights into consumer behavior and market dynamics.