Explain Empirical estimation models ?
https://www.computersprofessor.com/2017/08/explain-empirical-estimation-models.html?m=0
The COCOMO Models: Constructive
Cost MOdels
The COCOMO model is an hierarchy of
models as follows:
Model 1: The Basic
COCOMO model- computes software
development effort
and cost as a function of program
size expressed in
estimated lines of code.
Model 2: The Intermediate
COCOMO -computes software
development effort
and cost as a function of program
size and a set of
cost drivers that include subjective
assessments of
product, hardware, personel, and
project attributes.
Model 3: The Advanced
COCOMO model- incorporates all
characteristics of
the intermediate model with an
assessment of
the impact on each step of the
software development process.
The
COCOMO can be applied to three different kinds of software project classes:
Ø organic mode projects:
small, simple projects developed by small teams of software engineers, that
work with
less than rigid requirements;
Ø semi-detached mode projects:
medium in size and complexity projects, developed by teams with mixed
experience,that work with mixed requirements;
Ø embedded mode projects:
projects that have to be developed under tight hardware and software
constraints.
The Basic COCOMO equations have the following
form:
E = ab * (
KLOC )exp( bb )
D = cb *(
E )exp( db )
where: E is effort
in person-months
D is development time
in chronological months
the
coefficients are given in the table below:
Project class
|
ab
|
bb
|
cb
|
db
|
organic
|
2.4
|
1.05
|
2.5
|
0.38
|
semidetached
|
3.0
|
1.12
|
2.5
|
0.35
|
embedded
|
3.6
|
1.20
|
2.5
|
0.32
|
Example: Let the expected size of a semidetached software
project
is 33.3 KLOC. Using
the coefficients in the above table, the
BasicCOCOMO estimates can be produced
as follows:
E = ab * ( KLOC )exp( bb
)
= 3.0 * ( 33.3 )exp( 1.12 )
= 3.0 * 33.31.12
= 152 [person-months]
D = cb *( E )exp( db
)
= 2.5( 152 )exp( 0.35 )
= 2.5*1520.35
= 14.5 [months]
The
recommended number of people is:
N
= E / D
= 152 / 14.5
= 11 [people]
