1. Prepared by Stephen M. Thebaut, Ph.D. University of Florida
G&W Chapter 9: Reducing Ambiguity from Start to Finish Software Specification Lecture 16
Prepared by
Stephen M. Thebaut, Ph.D.
University of Florida

2. The Enemy and The Strategy
“THE fundamental problem of requirements definition is ambiguity.”
“…if we are ever to reduce problem statement ambiguity we’ll need tools to slow down the mind, tools to prevent us from racing ahead to try solving a problem prematurely.”
Software Specification: G&W Chapter 9

3. Heuristics can uncover sources of ambiguity due to variations in:
Observation: what people see or hear of a problem (intra-cluster variation).
Recall: what people remember of a problem (intra-cluster variation).
Interpretation: how people interpret a question, event, etc. (inter-cluster variation). See
Problem understanding: how people define the problem in their own mind (inter-cluster variation).
Software Specification: G&W Chapter 9

4. Software Specification: G&W Chapter 9
Ambiguity Poll
Create a metric that requires a solid understanding of the problem to estimate.
Give the problem statement (requirements) to informed individuals and ask them to independently estimate the value of the metric.
Bring the individuals together to compare and discuss the tabulated results.
Software Specification: G&W Chapter 9

5. Memorization Heuristic
Various individuals try to recall the problem statement precisely from memory. Parts that are not remembered well are likely to be places where meaning is not clear.
A variation is to ask individuals what they consider to be the critical parts of the problem statement. When the lists are combined and discussed, differences reveal potentially ambiguous parts.
Software Specification: G&W Chapter 9

6. “Mary had a little lamb” Heuristic
Software Specification: G&W Chapter 9

7. “Mary conned the trader” Heuristic
Mary owned a petite lamb.
Mary consumed a small amount of lamb.
Mary had a little lamb.
Mary conned the trader.
Mary was involved with a young sheep.
Software Specification: G&W Chapter 9

8. Prepared by Stephen M. Thebaut, Ph.D. University of Florida
G&W Chapter 9: Reducing Ambiguity from Start to Finish Software Specification Lecture 16
Prepared by
Stephen M. Thebaut, Ph.D.
University of Florida