Productive efficiency is a situation in which the economy could not produce any more of one good without sacrificing production of another good. In other words, productive efficiency occurs when a good or a service is produced at the lowest possible cost. The concept is illustrated on a production possibility frontier (PPF), where all points on the curve are points of productive efficiency. An equilibrium may be productively efficient without being allocatively efficient— i.e. it may result in a distribution of goods where social welfare is not maximized.