Email this page to a friend   

Email to a friend


(Alias: explanation, justification)

An explanation of the reasoning behind a decision, statement of requirement, design approach etc.

Rationales have the following objectives:

  • Communication. Rationales communicate the reasoning behind various requirements or development approaches to development teams
  • Make reasoning visible. If reasoning is made visible, defects in reasoning may be identified
  • Prevent loss of essential capabilities. The existence of rationales often prevents essential requirements/design components from being negotiated out after a passage of time when the reasons for there inclusion have been forgotten
  • Document dependencies. Rationales may be used to document the dependence of one capability on the existence of another thus preventing the introduction of inconsistencies by elimination or inappropriate modification
  • Prevent unnecessary rework. If the rationale behind a complex decision is not recorded it is often lost with the passage of time. In this case development teams often doubt the validity of the decision and set about repeating the reasoning process only to come to the same result
  • Support traceability. Rationales may be used to document the prior existing specification, design description, policy or procedure which triggered the need for a system component or capability.

Rationale Components

  • Issue. A problem, concern, or question that requires discussion for the problem solving to proceed
  • Position. A statement or assertion that responds to an issue
  • Argument. Statements that support or object to a position
  • Assumption. The basis for an argument
  • Decision. Resolving issues by selecting a position.

Rationale Component Relationships

Rational Relationships

An Example of a Rationale


Oxygen masks shall be deployed for use by passengers within five seconds of the cabin pressure dropping below 10 PSI.


  • Issue: how long does it take a passenger to become distressed through lack of oxygen?
  • Position 1: ten seconds at 10 PSI
  • Position 2: five seconds at 10 PSI
  • Argument: we don't want any distress
  • Assumption: any airline that causes its passengers distress goes out of business
  • Decision 1: choose five seconds at 10 PSI
  • Decision 2: this requirement is mandatory and nonnegotiable.

Member Comments


4 member ratings

✭ ✭ ✭ ✩ ✩

RE Definition: Rationale

project manager

By S.KUMAR » Sat 29-Jun-2013, 20:38, My rating: ✭ ✩ ✩ ✩ ✩

Technology has always driven what is possible in business. The fax machine, email, and the internet have each revolutionized the way in which businesses communicate. Similarly, advances in reporting and data visualization software have revolutionized ways in which people observe their businesses and make decisions. Today, the evolution of what is possible continues with the availability of Predictive Analysis from SAP. The ability to analyze vast amounts of historical data and create accurate projections of future trends is no longer the sole domain of data scientists and the academic elite. SAP has brought the power of predictive analysis to the business person.

4 Comments  • Page 4 of 4 •        Previous «  1   2   3   4 

- Rate this definition.
- Did it help?
- Suggest improvements.
- Request more information.
- Exchange ideas with our member community.

Email to a friend