efficiencytoinput

Efficiencytoinput, abbreviated ETI, is a proposed metric used in systems analysis to quantify how effectively input resources are transformed into useful outputs. It represents the ratio of a measurable useful output to the corresponding input resource and is typically expressed as a dimensionless number or percentage. Because inputs and outputs can be measured in different units, ETI requires normalization to a common value scale, such as monetary value, a utility score, or energy-equivalent terms.

Formula and measurement: ETI = Useful output value / Input resource value. The useful output value may be defined as revenue, cost savings, or utility gain, while the input resource value may be the total cost, energy consumed, or time invested. Depending on context, time horizon and quality adjustments may be included. For example, in manufacturing, input resources could be total production cost, while output value is the sale value of the produced goods; in software development, input is development cost and output value is projected lifetime revenue.

Applications: ETI is used in performance benchmarking, project evaluation, and sustainability assessments. It helps compare alternatives that have different resource footprints, focusing on value generation per unit input rather than gross output alone. It is particularly useful when multiple projects consume different kinds of resources or when a common currency is needed to weigh disparate benefits.

Limitations: ETI depends on chosen units and the quality of outputs; it can be manipulated by framing outputs or ignoring externalities; it does not inherently capture factors like risk, reliability, or social impact. It is best used alongside other metrics such as ROI, efficiency, and lifecycle analysis.

History and adoption: The term ETI appears in contemporary discussions in systems engineering and operations research as a flexible, non-standard metric. It has been proposed for cross-domain comparisons but lacks a universally accepted definition or standard methodology.

See also: efficiency, productivity, return on investment, cost-benefit analysis.