This document discusses major factors that influence software cost estimation. It identifies programmer ability, product complexity, product size, available time, required reliability, and level of technology as key factors. It provides details on how each factor affects software cost, including equations to estimate programming time and effort based on variables like source lines of code and developer months. Program complexity is broken into three levels: application, utility, and system software. The document also discusses how underestimating code size and inability to compress development schedules can impact cost estimates.

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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