Page 110 - DCAP305_PRINCIPLES_OF_SOFTWARE_ENGINEERING

Principles of Software Engineering

Notes 3. Reengineering COCOMO I needs:
(a) New software processes
(b) Applications composition
(c) Application generation capabilities
(d) Process-driven quality estimation
4. ........................ is for next phases or spiral cycles.
(a) Application composition model (b) Early design model
(c) Post-architecture model (d) None of these
5. The model of COCOMO-II is also called COCOMO’81 is presented.
(a) True (b) False

5.5 Development Effort Estimates

Following are the factors which effort the development:

5.5.1 Sizing
A good size estimate is vital for a good model estimate. However determining size can be
very demanding because projects are generally composed of new reused (with or without
modifications) and automatically translated code. The baseline size in COCOMO II is a count
of new lines of code.
SLOC is defined such that only source lines that are DELIVERED as part of the product are
included test drivers and other support software (-as long as they are not documented as carefully
as source code is excluded). One SLOC is one logical source statement of code (e.g. declarations
are counted, comments not) In COCOMO II effort is expressed as person months (PM). Person
month is the amount of time one person spends working on the software development project
for one month. Code size is expressed in thousands of source lines of code (KSLOC). The goal
is to measure the amount of intellectual work put into program development. Counting source
lines of Code (SLOC) takes account of new lines of code (reused code has to be adjusted). There
are two possibilities: either to count the source lines of code (with the Software Engineering
Institute (SEII) checklists or tool supported) or to count the unadjusted function points and to
convert them via “backfiring” tables to source lines of code. For further information on counting
the unadjusted function points (UFP) as well as the ratios for the conversion.

5.5.2 The Scale Factors

Most significant input to the COCOMO II model is size. Size is treated as a special cost driver
in that it has an exponential factor, E. This exponent is an aggregation of five scale factors. They
are only used at the project level for both the Early Design and the Post-Architecture model.
All scale factors have qualitative rating levels (‘extra low’ to ‘extra high’). Each scale factor is
the subjective weighted average of its characteristics.
The five Scale Factors are:
1. PREC Precedentedness (how novel the project is for the organization)

2. FLEX Development Flexibility
3. RESL Architecture / Risk Resolution
4. TEAM Team Cohesion

5. PMAT Process Maturity

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