Efficiency in general describes the extent to which time, effort or cost is well used for the intended task or purpose. It is often used with the specific purpose of relaying the capability of a specific application of effort to produce a specific outcome effectively with a minimum amount or quantity of waste, expense, or unnecessary effort. "Efficiency" has widely varying meanings in different disciplines.

The term "efficient" is very much confused and misused with the term "effective". In general, efficiency is a measurable concept, quantitatively determined by the ratio of output to input. "Effectiveness", is a relatively vague, non-quantitative concept, mainly concerned with achieving objectives. In several of these cases, efficiency can be expressed as a result as percentage of what ideally could be expected, hence with 100% as ideal case. This does not always apply, not even in all cases where efficiency can be assigned a numerical value, e.g. not for specific impulse.

A simple way of distinguishing between Efficiency and Effectiveness is the saying, "Efficiency is doing things right, while Effectiveness is doing the right things." This is based on the premise that selection of objectives of a process are just as important as the quality of that process.

A slightly broader mode of efficiency that nevertheless remains consistent with the "percentage" definition in many cases is to say that efficiency corresponds to the ratio r=P/C of the amount P of some valuable resource produced, per amount C of valuable resources consumed. This may correspond to a percentage if products and consumables are quantified in compatible units, and if consumables are transformed into products via a conservative process. For example, in the analysis of the energy conversion efficiency of heat engines in thermodynamics, the product P may be the amount of useful work output, while the consumable C is the amount of high-temperature heat input. Due to the conservation of energy, P can never be greater than C, and so the efficiency r is never greater than 100% (and in fact must be even less at finite temperatures).

Other articles related to "efficiency":

Material Efficiency
... Material efficiency is a description or metric which expresses the degree in which usage of raw materials, construction projects or physical processes are ... usable item out of thinner stock than a prior version increases the material efficiency of the manufacturing process ... The term Material efficiency can also signify the degree in which a material can handle a particular load, strain or weight upon it ...
Link Spectral Efficiency
... The link spectral efficiency of a digital communication system is measured in bit/s/Hz, or, less frequently but unambiguously, in (bit/s)/Hz ... Alternatively, the spectral efficiency may be measured in bit/symbol, which is equivalent to bits per channel use (bpcu), implying that the net bit rate is divided ... Link spectral efficiency is typically used to analyse the efficiency of a digital modulation method or line code, sometimes in combination with a forward error correction (FE ...
Efficiency - In Science and Technology - In Other Sciences
... In computing Algorithmic efficiency, optimizing the speed and memory requirements of a computer program Storage efficiency, effectiveness of computer data storage Efficiency factor, in data communications Efficiency ...
International Partnership For Energy Efficiency Cooperation
... The International Partnership for Energy Efficiency Cooperation (IPEEC) is a high-level international forum which includes developed and developing countries ... enhance global cooperation in the field of energy efficiency (EE) and to facilitate policies that yield energy efficiency gains across all sectors globally ... in May 2009 represents a key milestone in the improvement of energy efficiency, generally referred to as the use of the least amount of energy per ...

Famous quotes containing the word efficiency:

    “Never hug and kiss your children! Mother love may make your children’s infancy unhappy and prevent them from pursuing a career or getting married!” That’s total hogwash, of course. But it shows on extreme example of what state-of-the-art “scientific” parenting was supposed to be in early twentieth-century America. After all, that was the heyday of efficiency experts, time-and-motion studies, and the like.
    Lawrence Kutner (20th century)

    I’ll take fifty percent efficiency to get one hundred percent loyalty.
    Samuel Goldwyn (1882–1974)

    Nothing comes to pass in nature, which can be set down to a flaw therein; for nature is always the same and everywhere one and the same in her efficiency and power of action; that is, nature’s laws and ordinances whereby all things come to pass and change from one form to another, are everywhere and always; so that there should be one and the same method of understanding the nature of all things whatsoever, namely, through nature’s universal laws and rules.
    Baruch (Benedict)