Analytical models are mathematical models that provide closed form solutions. While there is significant ambiguity in describing the mathematical difference between analytical and numerical models, the definition here is determined by its use in Production System Optimization and Project Production Management. Specifically, analytical models provide closed formed mathematical solutions (equations) for project production system evaluation in contrast to discrete event simulations which are numerical solutions that model project production systems as a discrete sequence of events in time. Find an example of an Analytical Model related to Onshore Drilling Rig Fleet Size and Schedule here.