Uncertainty Analysis Guidebook
Zoë Stephenson
Technical Report YCS-2005-387, University of York, May 2005
Uncertainty analysis is a simple requirements analysis process that is intended for use whenever a designer perceives uncertainty on the part of the customer supplying the requirement. The process derives additional flexibility requirements that will help the designer to design an architecture that will withstand likely changes to the requirements because of that uncertainty. The following scenarios identify some of the benefits of this type of analysis:
  • When the requirements are difficult to use but progress must be made, the analysis provides a way of narrowing down the possibilities and reducing the problem so that it is easier to manage and the risks can be better estimated.
  • When a designer introduces a design that is structured for flexibility and change, the analysis provides a justification for the time spent producing that more flexible design in terms of potential changes that may be accommodated.
  • When the architecture is being subjected to inspection during safety analysis, the rationale and context for the flexibility will be clear.
In general, the problem that is being addressed is the situation where a final set of fully agreed requirements cannot be defined until relatively late in the project, and hence requirements changes occur throughout the course of development. The process not only identifies the likely changes that will need to be addressed, but also helps to plan a design solution that will be flexible with respect to those changes. The information about the indicators of the uncertainty can also be used in negotiations with the customer to help explain outstanding problems with the requirements.