Nelder–Mead simplex method (NM), originally developed in deterministic optimization, is an efficient
direct search method that optimizes the response function merely by comparing function values. While
successful in deterministic settings, the application of NM to simulation optimization suffers from two
problems: (1) It lacks an effective sample size scheme for controlling noise; consequently the algorithm
can be misled to the wrong direction because of noise, and (2) it is a heuristic algorithm; the quality of
estimated optimal solution cannot be quantified. We propose a new variant, called Stochastic Nelder–
Mead simplex method (SNM), that employs an effective sample size scheme and a specially-designed
global and local search framework to address these two problems. Without the use of gradient information,
SNM can handle problems where the response functions are nonsmooth or gradient does not exist.
This is complementary to the existing gradient-based approaches. We prove that SNM can converge to
the true global optima with probability one. An extensive numerical study also shows that the performance
SNM is promising and is worthy of further investigation.