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In statistics, efficiency is a measure of quality of an estimator, of an experimental design, [1] or of a hypothesis testing procedure. [2] Essentially, a more efficient estimator needs fewer input data or observations than a less efficient one to achieve the Cramér–Rao bound .
Efficiency is very often confused with effectiveness. In general, efficiency is a measurable concept, quantitatively determined by the ratio of useful output to total useful input. Effectiveness is the simpler concept of being able to achieve a desired result, which can be expressed quantitatively but does not usually require more complicated ...
Efficacy, efficiency, and effectivity are terms that can, in some cases, be interchangeable with the term effectiveness. The word effective is sometimes used in a quantitative way, "being very effective or not very effective". However, neither "effectiveness", nor "effectively", inform about the direction (positive or negative) or gives a ...
Two other commonly used F measures are the measure, which weights recall twice as much as precision, and the measure, which weights precision twice as much as recall. The F-measure was derived by van Rijsbergen (1979) so that F β {\displaystyle F_{\beta }} "measures the effectiveness of retrieval with respect to a user who attaches β ...
Overall equipment effectiveness [1] (OEE) is a measure of how well a manufacturing operation is utilized (facilities, time and material) compared to its full potential, during the periods when it is scheduled to run. It identifies the percentage of manufacturing time that is truly productive.
However, other effectiveness measures that can exceed 1.0 are used for refrigerators, heat pumps and other devices that move heat rather than convert it. It is not called efficiency, but the coefficient of performance, or COP. It is a ratio of useful heating or cooling provided relative to the work (energy) required.
PUE was introduced in 2006 and promoted by The Green Grid (a non-profit organization of IT professionals) in 2007, and has become the most commonly used metric for reporting the energy efficiency of data centres. [10] Although it is named "power usage effectiveness", it actually measures the energy use of the data centre. [10]
There are also other definitions and measures. All characterizations of economic efficiency are encompassed by the more general engineering concept that a system is efficient or optimal when it maximizes desired outputs (such as utility ) given available inputs.