Definition of Term: Multilevel Emulation

Multilevel emulation (or multiscale emulation) is the application of emulation methodology to problems where we have two or more versions of the same simulator that produce outputs at different levels of accuracy or resolution. Typically, the lower-accuracy simulators are less expensive to evaluate than the high accuracy models. Multilevel emulation seeks to supplement the restricted amount of information on the most-accurate model, with information gained from larger numbers of evaluations of lower-accuracy simulators to improve the performance of the final emulator.