The relation of outcomes, measured in a variety of ways, to the inputs required for that level of production. In business, efficiency of materials, energy, personnel, investment, and processes are commonly measured in order to measure performance and prioritize expenditures and projects. In sustainable business, a systems perspective requires addressing untraditional economic effects (such as lost energy though waste, lifecycle analysis of materials, toxicity of materials, and subsidies) as well as social and environmental effects in order to assess actually efficiency.