Price elasticity of demand

Price elasticity of demand describes how strongly quantity demanded responds to a price change. A common calculation divides the percentage change in quantity by the percentage change in price, producing a ratio without a currency unit.[1] State whether percentage changes use an initial-value or midpoint method and whether the sign or absolute value is reported.[1][2]

Falling sales after a price rise can also reflect a stockout or seasonal change. Use an appropriate comparison and document how percentage changes are calculated. An observed response applies to the tested price range, not necessarily to much larger changes.