In discrete event simulation concurrent estimation is a technique used to estimate the effect of alternate parameter settings on a discrete event system. For example from observation of a (computer simulated) telecommunications system with a specified buffer size                               B                      0                                  , one estimates what the performance would be if the buffer size had been set to the alternate values                               B                      1                          ,        …        ,                  B                      n                                  . Effectively the technique generates (during a single simulation run)                     n                 alternative histories for the system state variables, which have the same probability of occurring as the main simulated state path; this results in a computational saving as compared to running                     n                 additional simulations, one for each alternative parameter value.
The technique was developed by Cassandras, Strickland and Panayiotou.