1. כ"ז/שבט/תשע"ח
An Overview of Software Development Effort and Cost Estimation Techniques
Professor Ron Kenett
Tel Aviv University
School of Engineering

2. Software Cost Estimation Models
כ"ז/שבט/תשע"ח
Software Cost Estimation Models
TRW
Doty
Boeing
IBM-FSD
Rayleigh
SLIM
RCA Price/S
COCOMO 81
JPL

3. Software Cost Estimation Models
כ"ז/שבט/תשע"ח
Software Cost Estimation Models
Doty factors
IBM-FSD - 29 factors
COCOMO factors
JPL factors

4. Cost Adjustment Factors
כ"ז/שבט/תשע"ח
Cost Adjustment Factors
TRW
Easy
Medium
Hard
New module 1.0
Old module 0.7

5. Development Efforts (MM)
כ"ז/שבט/תשע"ח
Development Efforts (MM)
IBM-FSD W = 5.2 L^0.91
RADC W = 4.86 L^0.976
Doty W = 5.25 L^1.057
JPL W = 2.43 L^0.962

6. Staffing Size (Persons)
כ"ז/שבט/תשע"ח
Staffing Size (Persons)
IBM-FSD S = W^0.65
RADC S = W^0.641

7. Project Duration (Months)
כ"ז/שבט/תשע"ח
Project Duration (Months)
IBM-FSD T = 2.47 W^0.35
RADC T = 3.59 W^0.358
T = 4.55 L^0.349

8. COnstructive COst Model
כ"ז/שבט/תשע"ח
COnstructive COst Model
Barry Boehm
Software Engineering Economics
Prentice Hall, 1981

9. Basic COCOMO 81 Organic MM = 2.4 (KDSI)^1.05 TDEV = 2.5 (MM)^0.38
כ"ז/שבט/תשע"ח
Basic COCOMO 81
Organic MM = 2.4 (KDSI)^1.05
TDEV = 2.5 (MM)^0.38
Semidetached MM = 3.0 (KDSI)^1.12
TDEV = 2.5 (MM)^0.35
Embedded MM = 3.6 (KDSI)^1.20
TDEV = 2.5 (MM)^0.32

10. Intermediate COCOMO 81 Organic (MM)nom = 3.2 (KDSI)^1.05
כ"ז/שבט/תשע"ח
Intermediate COCOMO 81
Organic (MM)nom = 3.2 (KDSI)^1.05
TDEV = 2.5 (MM)^0.38
Semidetached (MM)nom = 3.0 (KDSI)^1.12
TDEV = 2.5 (MM)^0.35
Embedded (MM)nom = 2.8 (KDSI)^1.20
TDEV = 2.5 (MM)^0.32

11. COCOMO 81

12. COCOMO 81

13. COCOMO 81

14. COCOMO II, 1997 Challenges faced in calibrating COCOMO II
כ"ז/שבט/תשע"ח
COCOMO II, 1997
Challenges faced in calibrating COCOMO II
GUI builders, COTS, 4GL’s, reuse
– Need to rethink size metrics
Distributed interactive applications
– Web- based, object- oriented, event- based
– Middleware effects
New process models (evolutionary, incremental, spiral)
– Phases overlap
– Where are cost measurement endpoints?
Lack of good data
– not enough data (i. e. very little degrees of freedom)
– lack of dispersion
– heteroskedasticity

15. כ"ז/שבט/תשע"ח
COCOMO II
The 1997 version
– Multivariate Linear Regression with 10%weighted average of expert- determined and data-determined
The 1998 version
– Bayesian Regression Analysis
– Model more Data- Determined
The 19??/ 20?? version
– 100% Data- Determined

16. כ"ז/שבט/תשע"ח
COCOMO II
COCOMO II Calibration Process Began with expert- determined a- priori model parameters
– Iterated with Affiliates (Result => Original Post Architecture Model)
- Collected Data
- Identified and consolidated highly correlated model parameters
- Statistically determined estimates of consolidated model parameters from data
– Using logarithms to linearize regression
- Used data determined model parameters to adjust a- priori model parameters
– Experimented with weighting factors

17. כ"ז/שבט/תשע"ח
COCOMO II

18. כ"ז/שבט/תשע"ח
COCOMO II

19. COCOMO II Consolidated Highly Correlated Parameters
כ"ז/שבט/תשע"ח
COCOMO II
Consolidated Highly Correlated
Parameters
TIME
STOR
ACAP
PCAP
TIME STOR ACAP PCAP
• What do we do? Þ Combine :
TIME & STOR to give RCON (Resource Constraints)
ACAP & PCAP to give PERS (Personnel Factors)
Thus, 15 effort multipliers instead of 17 for calibration

20. כ"ז/שבט/תשע"ח
COCOMO II
Process Maturity does effect effort. A one increment change in PMAT (Level 1 Upper to Level 2, Level 2 to
Level 3, etc.) results in a 7% to 21% reduction in effort for a 30 KDSI project.
Effect is larger for larger products
Using it as a scale factor appears to provide a stronger influence on effort than as a multiplicative factor.
Its influence is less than the personnel capability of the team, about the same as product complexity (CPLX), and higher than other COCOMO cost drivers.
Process Maturity should be in all Software Cost
Estimation Models; it is well defined and measurable.
Some Observations on Effects of Process Maturity on Effort

21. כ"ז/שבט/תשע"ח
COCOMO II

22. כ"ז/שבט/תשע"ח
COCOMO II

23. כ"ז/שבט/תשע"ח
COCOMO II