Function Points IV EEE493 2000

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Function Points IV EEE493 2000
Royal Military College of Canada Electrical and
Computer Engineering

• Major Greg Phillips
• greg.phillips_at_rmc.ca
• 1-613-541-6000 ext. 6190

Dr. Scott Knight knight-s_at_rmc.ca 1-613-541-6000
ext. 6190
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Refs

• Pressman, R.S., Software Engineering a
  Practitioners Approach 5th Ed., McGraw-Hill,
  2001, Chapter 4
• Capers Jones, What are Function Points,
  www.spr.com/library/0funcmet.htm
• Boehm, Ray, Function Point FAQ, Software
  Composition Technologies, Inc., 1997,
  http//ourworld.compuserve.com/homepages/softcomp/
  fpfaq.htm
• Dreger, J.D., Function Point Analysis,
  Prentice-Hall, 1989

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Teaching Points

• Complexity Factors
• Backfiring
• Other Function Point Counting Systems

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Review

• When counting logical files or interfaces what do
  we mean by relationships that a class is aware
  of?
• Consider the following screen. What business
  function do you see?

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Print Part Inventory
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Function Points Summary Sheet
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Raw Function Points (unadjusted function points)

• The raw function point count measures what
  functionality is required of the system
• I.e. it measures how big the system is in terms
  of functionality
• It is not directly a measure of the effort
  required to build the system
• However, it is a major cost driver that effects
  this level of effort
• The count is the same regardless of who is
  building the system or the conditions under which
  the system is being built

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Adjusted Function Points

• If we imagine that we were always working with a
  nominal software development team working under
  nominal conditions then the function points would
  be a measure of effort.
• The situation on a particular project is seldom
  nominal in every way.
• We can adjust the function point count for our
  particular conditions.
• The result is to say that building our system
  would require the same effort as building a
  system with the adjusted count under nominal
  conditions.

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General Application Characteristics

• Production Environment Factors
• Data communications
• Distributed data and processing
• Performance objectives
• Heavily-used configuration
• Transaction rate
• On-line data entry
• End-user efficiency
• On-line update
• Complex processing
• Reusability
• Conversion and installation ease
• Operational ease
• Multiple-site use
• Facilitate change

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General Application Characteristics

• We count only those factors specifically approved
  by the user.
• We count only those factors that influence to a
  measurable degree the design, development,
  implementation or support of the application.
• See the handout for guidance on rating each
  Production Environment Factor.
• Each factor is rated from 0-5
• Total Degree of Influence (TDI) 0-70
• Nominal TDI 35

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Applying the Adjustment Factor

• Use the following formula
• where fpraw is the number of raw function points
• where fpadj is the number of adjusted function
  points fpadj fpraw (0.65 .01 TDI)
• The adjusted function points are measure of
  equivalent effort for a specific project
• I.e. the adjusted function points no longer
  directly indicate the size of the project

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So how big is our project in KLOC anyway??

• There exist tables that indicate how many
  statements of code it takes to implement a
  function point
• Obviously, this figure varies by computer
  language
• Is this a good idea?
• Some practitioners disagree with the idea of ever
  using KLOC as a measure and discourage such
  translation
• Being able to estimate the size of the project in
  KLOC is handy sometimes

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LOC to FP Translation Table
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Backfiring

• It should be possible to guess how many function
  points are implemented based on the number of
  lines of code
• For example, if you had an application consisting
  of 105,000 line COBOL program, these tables would
  lead you to believe that you had a 1,000 function
  point system
• But this approach can make a product design that
  is implemented with excessive amounts of code
  look like a functionally rich product
• adjusted or raw??

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Consider

• Function Point counting was developed by MIS
  developers, calibrated using MIS projects, and
  initially used to count MIS systems
• What is the maximum fluctuation in project effort
  using the adjustment formula

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Other Counting Systems

• Feature Points
• real-time process control, mathematical
  optimization and embedded systems
• adds an algorithm business function to the basic
  scheme and modifies weight factors
• Mk II Function Points
• 3D Function Points
• Real Function Points
• Object Points

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