Constraints, Limitations, and Assumptions
The TRADOC Analysis Center provides a useful handbook on constraints, limitations, and assumptions. For clarification, the following definitions are used:
- Constraint: A restriction imposed by the study sponsor that limits the study team's options in conducting the study.
- Limitation: An inability of the study team to fully meet the study objectives or fully investigate the study issues.
- Assumption: A statement related to the study that is taken as true in the absence of facts, often to accommodate a limitation.
There will generally be two sets of CLA: full and key. The full set should be maintained by the Study Team and many, typically those that have a minor impact on the study, may not be shared outside the team.Develop in order (Constraints, then Limitations, then Assumptions) Criteria: Necessary, Valid, Accepted*
"The study team must gain concurrence from the sponsor on those CLA that could significantly impact the study results. The study team may have to engage the sponsor more than once in reaching agreement on this initial 'key set' of CLA, but it is absolutely critical for facilitating the conduct of the study." [from the TRAC code of best practice]
CLA should be recorded as they become apparent. And they should be reviewed and updated continuously. They can be recorded in the Project Workbook as they are recognized by the Study Team. When offered to others they may be tailored to the audience: their may be some that are technical others that are non-technical. Rather than wasting time, the technical concerns can be raised with a audience that would find them interesting, and which )
Two obvious constraints are resources and available time to conduct the study. These are typically set by the sponsor. Indeed it is more typical that the sponsor will allocate a budget for the study and set a due date for a final report (which become contraits for the Study Team). Within these broad limits, the Study Team may have considerable latitude.In the defense and security arena, another constraint can be the security classification. This may rule out certain venues, or
Some potential limitations are:
• skill levels within the team (which may be ameliorated by a training plan, or by augmenting the team with appropriate experts
• data on weapon, sensor, or communications systems (which may require assumptions that a system which has unknown performance operates with the same characteristics as a well-known and similar system)
• computer-based simuations are running too slowly to provide timely results (which may necessitate running a number of situations in advance and using results from this to interpolate something for a faster response)