1. Software Reviews
Software reviews are the filter for the software engineering process
Applied at various different points and serve to uncover errors that can be removed
Purify the software engineering activities

2. Recap

3. Software Engineering II
Lecture 28
Fakhar Lodhi

4. Software Engineering II
Lecture 28
Fakhar Lodhi

5. The V-Model Requirements Acceptance Test Inspection Architecture
Integration Test
Inspection
Design
Unit Test
Inspection
The V-Model
Code
Inspection

6. Importance of reviews
“Technical work needs reviewing for the same reason that pencils needs erasers: To err is human. The second reason that we need technical reviews is although that people are good at catching errors, large class of errors escape the originator more easily than they escape anyone else”.
Freedman

7. Importance of reviews
A review – any review – is a way of using the diversity of a group of people to:
Point out needed improvements in the product of a single person or team
Confirm those parts of a product in which improvement is either not desired or no needed
Achieve technical work of more uniform, or at least more predictable, quality than can be achieved without reviews, in order to make technical work more manageable.
Freedman

8. Defect Removal Efficiency Jones 1997
Design Inspection
Code Inspection
Quality Assurance
Testing
Worst
30%
37%
50%
55%
65%
75%
77%
85%
95%
Median
40%
53%
70%
80%
87%
90%
97%
99%
Best
60%
93%
99.9%
Sample size – 1500 projects

9. Defect Amplification Model
Defects
Detection
Errors from
previous step
Errors Passed
Through
Percentage
Efficiency
for error
detection
Errors passed
To next step
Amplified Errors
1:x
Newly generated
errors
Development Step

10. 10 37 94 0% 6 0% 10 20% 4 *1.5 27 * 3 10 25 25 Preliminary Design
Errors passed through
Amplification Factor
Errors detected in this stage
Errors detected in this stage
Amplified Errors 10 37 94 0% 6 0% 10
20%
Newly generated errors
4 *1.5
27 * 3
Errors passed to next step
Errors passed to next step = *116 = 94
Errors passed to next step 10 25 25
Errors detected in this stage
Preliminary Design
Detailed Design
Code /Unit test
Total Errors/Defects 6+4* = 37
Total Errors/Defects 10+27*3+25 = 116
Errors passed to next step = 94 – 0.5*94 = 47
Errors passed to next step = 47 – 0.5*47 = 24 94 47 24 12 94
50% 47
50% 24
50%
Final Defects left unidentified
Errors detected in this stage
Errors detected in this stage
Integration test
Validation test
System test
Errors detected in this stage
Total Defects = 47

11. After Introducing Inspections at the Design and Code Level
Errors passed to next step =
*29= 15
Errors passed to next step =
*60= 24
Errors detected in this stage 3 15 24
70% 2
50% 5
60%
1 *1.5
10 * 3 10
Errors passed to next step 25 25
Preliminary Design
Detailed Design
Code /Unit test
Total Defects =29
Total Defects 5+10*3+25=60 24 12 6 3 24
50% 12
50% 6
50%
Integration test
Validation test
System test