The Constructive Cost Model (COCOMO) is an algorithmic software cost estimation model developed by Barry Boehm. The model uses a basic regression formula, with parameters that are derived from historical project data and current project characteristics. Basic COCOMO compute software development effort (and cost) as a function of program size. Program size is expressed in estimated thousands of source lines of code (SLOC, KLOC).

1. COCOMO MODEL
Software Engineering
Prepared
By
Devan Sharma

2. COCOMO Model
COCOMO was first published in 1981 Barry W. Boehm's Book Software
engineering economics
Fig : 1 W.Boehm

3. COCOMO Model
COCOMO model is used to estimate size ,cost and time of software to be
developed
Cost Size
Time
Fig 2: Need of COCOMO

4. COCOMO MODEL Types
Type of software
Semidetached
Organic Embedded

5. COCOMO
Mode Project size Nature of Project
Organic Typically
2-50 KLOC
Small size project, experienced
developers in the familiar
environment. For example, pay
roll, inventory projects ,Banking system
Semi
detached
Typically
50-300 KLOC
Medium size project, Medium
size team, Average previous
experience on similar project.
For example: Utility systems
like compilers, database
systems
Embedded Typically over
300 KLOC
Large project, Real time
systems, Complex interfaces,
Very little previous experience.
For example: ATMs, Air Traffic
Control ,Navigation satellite
Table 1: The comparison of three COCOMO modes

6. Person-Month
• Person-month (PM) is considered to be an appropriate unit for
measuring effort

7. COCOMO MODEL
The Constructive Cost Model (COCOMO)
Constructive Cost model
(COCOMO)
Basic Intermediate Complete(detailed)
Model proposed by
B. W. Boehm’s
through his book
Software Engineering Economics in 1981

8. COCOMO MODEL
Basic Model
Basic COCOMO model takes the form
E=ab(KLOC) PM
bb
db
D=cb (E)
where E is effort applied in Person-Months, and D is the
development time in months. The coefficients ab, bb, cb and db are
given in table
Months

9. Fig 3: COCOMO Model equation

10. Effort versus product size.
Fig 4 : Graph for effort

11. Development time versus size.
Fig 4 : Graph for Time

12. Disadvantages of Basic COCOMO Model
• It considers only KLOC to estimate effort
• It can not be used for modern tools
• It does not consider different parameters
Note : Intermediate COCOMO model considers different
parameters to estimate effort and time

13. COCOMO MODEL
Intermediate Model
Cost drivers
(i) Product Attributes
Required s/w reliability (accuracy)
Size of application database
Complexity of the product
(ii) Hardware Attributes
Run time performance constraints
Memory constraints
Speed of system

14. COCOMO MODEL
(iii) Personal Attributes
Analyst capability
Programmer capability
Application experience
Virtual m/c experience
Programming language experience
(iv) Project Attributes
Modern programming practices
Use of software tools

15. COCOMO model
Disadvantage of basic and intermediate COCOMO model
• A major shortcoming of both the basic and the intermediate
COCOMO models is that they consider a software product as a
single homogeneous entity.
• Now these days large software systems are made up of several
smaller sub-systems or modules with different characteristics.

16. Complete COCOMO model
• The complete COCOMO model considers different subsystems
of the software
• For example CU website has different modules or subsystem
 Graphical user interface (Front End)
 Database (your data is stored )

17. Complete COCOMO model
• Different modules or subsystems of the complete COCOMO model
Database part
 Graphical user interface (GUI) part
 Communication part
 Communication part can be considered as embedded software.
 The database part could be semi-detached software
 The GUI part organic software.
The costs for these three components can be estimated separately, and
summed up to give the overall cost of the system