The scope of the present work is to formulate a new model for the supply chain based on state space variables (HS3CM). The advantage of this model with respect to the Discrete Event Dynamic System (DEDS) are its linearity and the possibility of applying estimation techniques to better evaluate the lead time and commercial forecast. There are two major influences which can be derived by HS3CM. The first is the stock variation which is straightforward and the second is the lead time variation in which an heuristic approach was used. To demonstrate that the heuristic approach is valid we compared the state space model simulation against the ARENA simulation which utilizes DEDS directly with a perfect matching.