Own-Price Elasticity of Demand .Q: Why not just use the slope of a demand curve to measure the sensitivity of quantity demanded to a change in a commodity' s own price? A: Because the value of sensitivity then depends upon the(arbitrary) units of measurement used for quantity demandedOwn-Price Elasticity of Demand ◆Q: Why not just use the slope of a demand curve to measure the sensitivity of quantity demanded to a change in a commodity’s own price? ◆A: Because the value of sensitivity then depends upon the (arbitrary) units of measurement used for quantity demanded