1. Measuring the Progress of Projects
Using the Time Dependence of Code
Changes
Omar Alam, Bram Adams and Ahmed E. Hassan
Software Analysis and Intelligence Lab (SAIL), Queen’s University, Canada
1

2. Tracking the Progress of Projects
2
Managers track projects through:
Manually compiled progress reports
Meetings with developers

3. Software as a Construction Project
Each change provides structure
which other changes can build on
3

4. Approach: Establishing Time Dependence Between
Changes
Time dependent Time dependent
4

5. Approach: Establishing Time Dependence Between
Changes
C1 C2 C3 C4 C5 C6 C7 C8 C9 C10 C11
Period1 Period2 Period3
5

6. Approach: Establishing Time Dependence Between
Changes
C1 C2 C3 C4 C5 C6 C7 C8 C9 C10 C11
Period1 Period2 Period3
6

7. Approach: built-on-new, built-on-old and independent
changes
Built-on-old
Built-on-new
C1 C2 C3 C4 C5 C6 C7 C8 C9 C10 C11
Independent
Period1 Period2 Period3
7

8. Categories of Changes
8
Built-on-New
Independent
Built-on-Old

9. Case Study
1997-2007
1994-2005 9

10. Definition of built-on-new and built-on-old
The average plateaus when moving to periods longer
than two quarters 10

11. Just-in-time or Delayed?
?
11
Q1 How does the Time Dependence of Changes Vary?

12. Q1 : How does the Time Dependence of Changes Vary ?
12

13. PostgreSQL
Built-on-New Built-on-New
Built-on-Old
FreeBSD
13

14. Skyscrapers or Urban Sprawl
?
14
Q2: What is the Impact of Independent Changes?

15. Q2: What is the Impact of Independent Changes?
15

16. PostgreSQL
FreeBSD
16

17. Construction or Renovation?
same
floor or
different
floors?
17
Q3: Is the Distribution of Time Dependence Similar for the
Regular Development and Bug Fix Processes?

18. Q3: Is the Distribution of Time Dependence Similar for
Regular Development and Bug Fix Processes?
Correlations between bug fix and enhancement changes
PostgreSQL FreeBSD
Built-on-New 0.87 0.81
Built-on-Old 0.90 0.91
Independent 0.84 0.90
18

19. Same or Different Floors?
PostgreSQL and FreeBSD
19

20. Risks of Construction?
20
Q4: Is building on new code risky?

21. Q4: Is Building on Recent Changes Risky?
Correlation is 0.91 for FreeBSD
21
years

22. Q4: Is Building on Recent Changes Risky?
Correlation is 0.65 for PostgreSQL
22
years

23. Is Building on New Code Risky?
Building on new code is risky
Yes
23

24. 24
PostgreSQL FreeBSD
Built-on-New
Built-on-New
Built-on-Old
Fewer independent changes More independent changes
Conclusion

25. 25
Building on New Code
Risky and leads to bugs
Regular Development and Bug Fix
On same change periods
Conclusion