|aThe pressure to reduce product development time has increased due to rapidly changing technology and customer's needs. Therefore, a shortened product development time has become a critical issue for many enterprises. Being first to market is a major strategy for establishing product identity and capturing market share. Axiomatic design can be used to structure the design processes and reduce the complexity of product development. Using a hierarchical design structure tree (DST) created using design axioms, several theorems have been derived for modeling the product development process. These theorems capture successive iterations of design activities and provide a basis for a hierarchical probabilistic model-generating (HPMG) algorithm. This algorithm can be used to generate probabilistic models for every task in a DST. These models provide a mechanism to forecast the expected time window of a design project or design tasks in a project and assess the impact of design decisions. In addition, the derived theorems and the developed algorithms can also be employed to predict a general process with a hierarchical tree structure in which certain assumptions are made.