A method enables multiuser and distributed “what you see is what you get” probabilistic simulation. A method projects a problem P into k sub-problem spaces with at least 1 dimension, and executes the sub-simulations for each sub-problem in parallel with user's model initialization and parameterization process. A method utilizes “Simulate As You Operate” (SAYO) and “Batch Generation Batch Computation” (BGBC) techniques to perform data retrieval, random number generation and simulation in parallel with the user's model initialization and parameterization process. An apparatus only repeats the simulation process on the affected part of the model and holds the model inputs/outputs of unaffected part of the model fixed. A communication protocol allows users at different sites or different organizations to perform real-time simulations on the same model. An apparatus enables a process of sharing and benchmarking the model-associated statistics by aggregating and publishing the submitted information by users.