Floating Task: Introducing and Simulating a Higher Degree of Uncertainty in Project Schedules

Despite several attempts to accurately predict duration and cost of projects, simulation models in use are still over simplified and nonrealistic. They often fail to cope with real-life scenarios and uncertainty. In this paper we use the proxel-based simulation method to analyze and predict duration of project schedules exhibiting high uncertainty due to typical on-the-fly human decision behavior. The proxel-based simulation is an approximate simulation method that is more precise than discrete-event simulation. To model uncertainty, we introduce a new type of task, state-dependent (floating) task that supports and demonstrates a high degree of uncertainty and depends on various parameters in the schedule. For example, the probability distribution of the duration of a task can change depending on the team that performs it. Thus, this kind of task can be used to model the frequent re-scheduling in a project. We use software development process to illustrate our approach.