Tabular method for examining the changes in the efficiencies of a set of units over time. A set of time periods (1 ..t) is chosen and the efficiency of each unit (1..n) is computed separately for each period so that the efficiency of a given unit over each period is treated as a new unit resulting in a total number of tn units.

A factor which describes the amount of goods, services or other outcome obtained as a result of the processing of resources. Also, any factor which describes the qualitative nature of the resulting outcome.

The additional improvement (increase in outputs and/or decrease in inputs) needed for a unit to become efficient.

In an output-oriented model, an inefficient unit is made efficient through the proportional increase of its outputs, while the inputs proportions remain unchanged.

The input and output values that would render an inefficient unit relatively efficient. Thanassoulis and Dyson (1992) examine ways of modifying the DEA model so as to set priorities over which targets should be improved. [Thanassoulis E and Dyson R G (1992) ‘Estimating preferred target input-output levels using data envelopment analysis’, J. of Opi. Res., 56, pp 80-97.]

Same as aggregate efficiency

An efficiency measure that ignores the impact of scale-size by comparing a DMU only to other units of similar scale. Technical efficiency is computed using the BCC model. Overall efficiency is sometimes referred to as technical efficiency as closely follows the concept of technical efficiency developed by Farrell (1957), which technical efficiency as defined here, is known as ‘pure technical efficiency’. [Farrell M J (1957), ‘The measurement of productive efficiency’, J. Roy. Statist. Soc., 120, pp 253-290.]

Simply stated, a unit is Pareto-efficient when an attempt to improve on any of its inputs or outputs will adversely affect some other inputs or outputs. Formally, Chames et al (1981) consider a DMU to be 100% efficient only when ‘none of its inputs can be decreased without either (i) decreasing some of its outputs, or (ii) increasing some of its other inputs, and none of its outputs can be increased without either (i) increasing one or more of its inputs or (ii) decreasing some of its other outputs’. Since the condition for Pareto-efficiency is that a DMU’s efficiency score is 1, efficiency and Pareto-efficiency are synonymous. [Chames A, Cooper W W and Rhodes E (1981), ‘Evaluating program and managerial efficiency: an application of data envelopment analysis to program follow through’, Mgmt. Sci., 6, pp 668-697.]

The operational practices (a combination of the management and engineering knowledge) that determine how a DMU’s inputs are transformed into outputs.

Another name for reference set