1. Software Estimating Technology: A Survey
Richard Stutzke
Crosstalk, May96
text pp

2. Cost Estimation
An estimate of the effort and duration, associated costs of equipment, travel and training and the rationale for the calculations

3. Problem
“The estimator must estimate the effort (person-hours) and duration (calendar-day) for the project to enable managers to determine improtant business measures such as product costs, return on investment, and time to market.”

4. Recommendation
If you are involved with cost estimation, I recommend the following book
Tom DeMarco, Controlling Software Projects, Yourdon Press, NY c1982

5. Definition of Estimate (DeMarco)
Default:
"An estimate is the most optimistic prediction that has a non-zero probability of coming true"
Proposed:
"An estimate is a prediction that is equally likely to be above or below the actual result"

6. Estimates should not become goals
DeMarco argues that the estimation and the management decision about pricing or goals should be separate.

7. Estimate

8. Parametric Cost Estimation
LOC models
Boehm's COCOMO
Putnam's Model (SLIM)
non-LOC models
Function Points
combination
COCOMO2

9. Prediction Formulas
b>1
E=aXb
b<1

10. Boehm's COCOMO
Software Engineering Economics – article (1983) pp in text
Software Engineering Economics – (book) Prentice-Hall c1981
type COCOMO in a search engine - many www sites

11. COnstructive COst MOdel
Basic
macro - overview of whole project with one metric of KSLOC
Intermediate
multiplicative adjustment factors
Detailed
applying model to each phase

12. Modes of Software Development
Organic
detached, often batch
Semidetached
e.g. transaction processing
Embedded
e.g. os kernel

13. Programmer Effort Application Programs Utility Programs
PM = 2.4 * (KDSI)1.05
Utility Programs
PM = 3.0 * (KDSI)1.12
Systems Programs
PM = 3.6 * (KDSI)1.20
Note A’s in text are different from later versions of COCOMO

14. Example for effort Size Appl Util Sys 5K 13.0 18.2 24.8

15. Development Time (Months)
Application Programs
TDEV = 2.5 * (PM) 0.38
Utility Programs
TDEV = 2.5 * (PM) 0.35
Systems Programs
TDEV = 2.5 * (PM) 0.32

16. Example for development time
size appl util sys 5K
10K
15K
20K
25K
30K
35K
40K
45K
50K

17. Average Staffing Levels
Calculate by dividing PM by TDEV

18. Example for staffing levels
size appl util sys 5K
10K
15K
20K
25K
30K
35K
40K
45K
50K

19. COCOMO Effort Multipliers
product attributes
required reliability
data-base size
product complexity
computer attributes
execution time constraint
main storage constraint
virtual machine volatility
computer turnaround time

20. The Cocomo 2.0 Software Cost Estimation Model
Barry Boehm, etal
See web pages