about software cost estimation factor

1. SOFTWARE ENGINEERING
SOFTWARE COST FACTOR
B.Abinaya Bharathi,
II-M.Sc[Cs&IT],
Nadar Saraswathi college of Arts and Science,
Theni.
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2. SOFTWARE COST ESTIMATION
 One of the important and difficult task is estimating a
software product
 Preliminary estimate is prepared during planning
 •Improved estimate is presented at the software
requirements review
 •Final estimate is prepares at the preliminary design
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3. MAJOR FACTOR THAT INFLUENCE
SOFTWARE COST
 Programmer ability
 Product complexity
 Product size
 Available time
 Required reliability
 Level of technology
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4. PROGRAMMER ABILITY
 Maintaining and production of a software is based on
programmer
 Programmer must be expert in computer programming
 If not an expert project may become failure
 Programming is a individual and private activity
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5.  Communication path among programmers increases
according to the number of programmers in a project
 By Brook’s observation
Communication path=n(n+1)/2
 n= number of programmers
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6. PRODUCT COMPLEXITY
 Three main categories or three levels are
 Application software
 Utility software
 System software
.
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7.  Application software
 Developed using high level programming language
like C++,java etc,.
 Utility software
 Utility programs are system software like loader ,
linker , compiler
 System software
 Which directly interacts with hardware
 Ex: operating System 7

8.  By Brook’s observation
 1:3:9
 i.e. utility program are 3 times difficult than
application program.
 System program are 9 times difficult than utility
program.
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9.  By Boehm's observation
Three levels are
 Organic- application program
 Semi-detached- utility program
 Embedded-system program
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10.  Boehm derived an equation by analyzing the historical
data of many project
 Application program= PM*(KDSI)**1.05
 Utility program = PM*(KDSI)**1.12
 System program = PM*(KDSI)**1.20
*KDSI=thousand of delivered source line
*PM=Programmer month
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12.  Above graph shows that
 Developing a application program using 60,000 lines
 The ratio is 1 to 1.7 to 2.8 for application program ,
utility program and system program.
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13.  The development time for a product
 Application program TDEV=2.5*(PM)**0.38
 Utility programs TDEV=2.5*(PM)**0.35
 System programs TDEV=2.5*(PM)**0.32
*TDEV – development time
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14. 14
Graph shows that the duration
for developing all the three
types of system are same

15.  Total programmer for a project
 Application program:176.6PM / 17.85mo
=9.9programmers
 Utility program:294PM / 18.3mo
=16programmers
 System programm:489.6PM / 18.1mo
=27programmers
*mo=month
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16.  Failures in estimating the number of source
instructions in a software product is to under estimate the
amount of house keeping code
 Housekeeping code
 portion of source code
 handles input , output , interactive user
communication ,error checking and error handling
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17. PRODUCT SIZE
 A large software product is more expensive to develop
than a small one.
 Boehm equation indicate that
 “the rate of increase in required effort grows with
number of source instruction at an exponential”
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18. EFFORT EQUATION SCHEDULE EQUATION REFERENCE
 PM=5.2(KDSI)**0.91 TDEV=2.47(MM)**0.35
 PM=4.9(KDSI)**0.98 TDEV=3.04(MM)**0.36
 PM=1.5(KDSI)**1.02 TDEV=4.38(MM)**0.25
 PM=2.4(KDSI)**1.05 TDEV=2.50(MM)**0.38
 PM=3.0(KDSI)**1.12 TDEV=2.50(MM)**0.35
 PM=3.6(KDSI)**1.40 TDEV=2.50(MM)**0.32
 PM=1.0(KDSI)**1.50
 PM=0.7(KDSI)**1.50
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19. AVAILABLE TIME
 Project must complete within the given time and cost
 Putnam’s
 “project effort is inversely proportional to the fourth
power of the development time”
 E=k/(TD**4)
 Putnam states that , development schedule
 cannot be compressed below about 86%
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20.  Boehm states that
 “there is a limit beyond which a software project
cannot reduce its schedule by buying more personnel
and equipment”
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21. REQUIRED RELIABILITY
 Four main terms that express the reliability are
 Accuracy
 Robustness
 Completeness
 Consistency
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22.  A product which is built by these all characteristics but
there is a cost associated with different phases to ensure
high reliability
 Product failure may cause slightly inconvenience high
financial loss or risk to human life
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23. LEVEL OF TECHNOLOGY
 A software Project is mainly reflected by
 programming language
 abstract machine
 programming practices
 software tools used
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24.  •In Modern programming languages to increase
productivity and software reliability ,additional
features like
 strong type checking
 data abstraction
 separate computation
 exception handling
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25.  •Programming practices include
 systematic analysis and design technique
 structure designed notations
 inspection
 structured coding
 systematic testing
 program development library
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26.  Software tools are
 Assemblers
 Loaders
 Compilers
 Other interactive tool
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27. THANK YOU
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