M. Rostamy-malkhalifeh - Department of Mathematics, Science and Research Branches, Islamic Azad University, Tehran, Iran,
L. Javidan - Department of Mathematics, Science and Research Branches, Islamic Azad University, Tehran, Iran,
Z. Aghababazadeh - Department of Mathematics, Science and Research Branches, Islamic Azad University, Tehran, Iran,
M. Allahyar - Department of Mathematics, Science and Research Branches, Islamic Azad University, Tehran, Iran,

The evidence of congestion is seen in the performance of the under-evaluated unit wheneverreductions in one or more inputs are associated with increases in one or more outputs without causing any deterioration in any of the other inputs or outputs.Detection and calculation of this phenomenon is of paramount importance from an economical point of view. This current paper presents a new definition for congestion based on which, it develops an algorithm and a geometrical method to study the possible existence of congestion and to identify its resources in decision making units (DMUs) without solving the model. Finally, the results obtained through the suggested methods with those obtained by solving models given in DEA literature are compared using some numerical examples

Data envelopment Congestion, Efficiency