The QI Stochastic Model window provides you with the power to generate different sets of interfaces based on various upper and lower-layer lithologies/litho-fluids. The QI Stochastic Model window runs a probability analysis based on the set of interfaces and produces useful results in AVO classifications. 

Interface (reflector) refers to the boundary between two different rock layers, each with their respective elastic properties. The rock layers can be a reservoir, non-reservoir, or any user-defined litho-fluid combination. 

When generating interfaces, the upper layer is usually kept the same and is often a non-reservoir lithology. In some instances, it can be useful to have two different upper-layer non-reservoir lithologies.

The QI Stochastic Model window can use the interface generated for stochastic amplitude variation with offset (AVO) analysis, which is a variation in seismic reflection amplitude with a change in distance between the shot point and receiver (offset).