Economic efficiency is described as the ratio of economic outputs to economic inputs. This is analogous to mechanical efficiency, which is power (watts, horsepower etc.) output over power input. Since much economics these days has the look and feel of "the study of business," outputs are understood to be the goods (products and/or services) produced by a business, and inputs are understood to be things (assets) the business spends money on, evidently as means to the end of creating these products.