The impact of uncertainty and ambiguity related to iteration and overlapping on schedule of product development projects

• Propose that the iteration and overlapping are the main causes of uncertainty and ambiguity
• Present a simulation method to analyze uncertainty and ambiguity of PD project
• A case study reveals how uncertainty and ambiguity impact on project schedule.

Overlapping and iteration stemming from concurrent engineering are fundamental features of product development (PD) projects. They may not only reduce project duration but also create process uncertainty and ambiguity. We propose that the iteration and overlapping are the main causes of uncertainty and ambiguity in the PD process. Based on discrete-event simulation modeling and analysis with Arena software, our empirical research provides a quantitative method to reveal how uncertainty related to iteration and ambiguity related to overlapping impact on project schedule. In the simulation model, we use four variables to characterize uncertainty: iteration probability, iteration length, number of iterations and activity's learning curve effect. And different sequential and overlapped process structures are used to describe the variable of ambiguity in the model. Propositions regarding the reduction of uncertainty and ambiguity by controlling iteration and overlapping are derived. Simulation experiment results yield and reinforce several managerial insights, including: the relationship between uncertainty or ambiguity reduction and the complexity of iteration or levels of overlapping; and how to control project schedule and hedge the risk resulting from overlapping and iteration.