yksikköelastic

Yksikköelastic, or unit elasticity, is a term used in microeconomics to describe a specific degree of responsiveness of quantity demanded to price changes. A demand is described as unit elastic when a 1% change in price leads to a 1% change in the quantity demanded in the opposite direction, so the magnitude of the price elasticity of demand is one.

The formal measure is the point price elasticity of demand, defined as E_d = (dQ/dP) × (P/Q). When E_d = -1, the demand is unit elastic (using the common sign convention for downward-sloping demand). If one focuses on magnitude rather than sign, unit elasticity is expressed as |E_d| = 1. Elasticity can differ along a curve; unit elasticity is a property at a specific point rather than a universal characteristic of the entire demand function.

In terms of revenue, unit elasticity implies that total revenue remains approximately unchanged for small price changes at that point, because the percentage change in quantity sold offsets the percentage change in price. For larger changes, the effect on revenue depends on the curvature of the demand curve and the actual price–quantity pair.

Unit elasticity is often contrasted with elastic demand (|E_d| > 1), where price increases reduce revenue, and inelastic demand (|E_d| < 1), where price increases increase revenue. Along most smooth demand curves, elasticity varies with price and quantity, so a single good can be unit elastic only at specific points. The concept also has parallels in other elasticities, such as income or cross-price elasticity, but is most commonly discussed in the context of price and quantity demanded.