1. Software Economics Phase Yield
Emerson Murphy-Hill
Creative Commons Attribution 4.0 License.
Material Created by NCSU Software Engineering Faculty.

2. Fault removal yield
Phase yield = removed in phase removed in phase + escapes from phase
Phases: design review, code, code review, compile, test
Phase escapes: defects injected before or during the phase, not found before or during the phase, and found later
The “escapes from phase” measure cannot be precisely calculated until after the program has been used in the field (need post-development defects) – need 20/20 hindsight
even then some failures can surface for years

3. Fault Removal Yield Example
Phase
Injected
Removed
Cumulative Injected
Cumulative Removed
Requirements 1
Design 5 6
Design Review 3
Code 15 21 4
Code Review 8 12
Static Analysis 18
Test
Field
Total 26
Note: the faults show up in the “injected” column if they were analyzed and removed prior to release.
Design Review Yield = 3/(0+6) = 50%
Code Review Yield= 8/(8+9) = 47%
Process Yield = 21/26 = 81%

4. Quality Assurance Filters - Examples
100 errors
Inspection
(50%)
50 errors
Testing (50%)
25 errors To
customer
Solo programming with inspection
Testing
To customer
Testing (50%)
Solo programming without inspection or pair programming
Pair Programming
Paired team without inspection
See course pack page 23