Information Systems Analysis and Design

1
Information Systems Analysis and Design
Information Systems
Section A
CHAPTER 9
PARSONS/OJA
Page 442
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Information Systems Analysis and Design
Chapter 9
Chapter PREVIEW

• Describe how information systems help
  organizations fulfill their missions, deal with
  threats, and take advantage of opportunities
• Contrast and compare the characteristics of
  office automation systems, transaction processing
  systems, management information systems, decision
  support systems, and expert systems
• Describe various models for the system
  development life cycle (SDLC)

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Information Systems Analysis and Design
Chapter 9
Chapter PREVIEW

• List the activities that take place in each phase
  of the system development life cycle
• Apply the PIECES framework to classify problems
  that reduce the effectiveness of an information
  system
• Describe alternative hardware and software
  solutions that a project team might typically
  consider
• Explain the differences between unit testing,
  integration testing, system testing, and
  acceptance testing

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Information Systems Analysis and Design
Chapter 9
Chapter PREVIEW

• Describe the advantages and disadvantages of
  direct conversion, parallel conversion, phased
  conversion, and pilot conversion
• Explain the feedback mechanism that helps system
  operators identify and fix bugs

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Information Systems
Section A
Chapter 9
Information Systems in Organizations What is
an information system?

• An information system collects, stores, and
  processes data to provide useful, accurate, and
  timely information, typically within the context
  of an organization
• The term information system always refers to a
  system that uses computers, and usually includes
  communications networks

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Information Systems
Section A
Chapter 9
Whats the official definition of
organization?

• An organization is a group of people working
  together to accomplish a goal
• Any organization that seeks profit by providing
  goods and services is called a business
• Some organizations are formed to accomplish
  political, social, or charitable goals that do
  not include amassing profit
• These organizations are known as nonprofit
  organizations

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Information Systems
Section A
Chapter 9
Whats the official definition of
organization?

• Every organization has a goal or plan thats
  often referred to as its mission
• A mission statement describes not only an
  organizations goals, but also the way in which
  those goals will be accomplished

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Information Systems
Section A
Chapter 9
Whats the official definition of
organization?
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Information Systems
Section A
Chapter 9
Who uses information systems?

• An information system is used by the people in an
  organization and its customers
• Not everyone in an organization uses an
  information system in the same way
• An organizational chart depicts the hierarchy of
  employees in a typical organization
• Workers are the people who carry out the
  organizations mission
• Managers determine organizational goals and plan
  how to achieve those goals

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Information Systems
Section A
Chapter 9
Who uses information systems?

• This emphasis on long-range and future goals is
  referred to as strategic planning
• Mid-level managers set incremental goals that can
  be achieved in a year or lessa process referred
  to as tactical planning
• Low-level managers are responsible for scheduling
  employees, ordering supplies, and other
  activities that make day-to-day operations run
  smoothlya process referred to as operational
  planning

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Information Systems
Section A
Chapter 9
Who uses information systems?
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Information Systems
Section A
Chapter 9
How do information systems help the people in
an organization?

• An information system can help the people in an
  organization perform their jobs more quickly and
  effectively by automating routine tasks
• One of the major functions of an information
  system is to help people make decisions in
  response to problems
• All problems are not alike, but they can be
  classified into three types structured,
  semi-structured, and unstructured

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Information Systems
Section A
Chapter 9
How do information systems help the people in
an organization?

• An everyday, run-of-the-mill, routine problem is
  called a structured problem
• A semi-structured problem is less routine than a
  structured problem
• An unstructured problem requires human intuition
  as the basis for finding a solution
• An information systems ability to assist with
  problem solving and decision making depends on
  the data that it collects and then makes available

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Information Systems
Section A
Chapter 9
How do information systems help organizations
carry out their missions?

• Most organizations exist in a rapidly changing
  and competitive environment, where many
  opportunities and threats can be effectively
  handled only by using computers
• To be successful in its mission, an organization
  must respond effectively to opportunities and
  threats.
• An organization has a choice of three
  fundamental responses

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Information Systems
Section A
Chapter 9
How do information systems help organizations
carry out their missions?
Click to start
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Information Systems
Section A
Chapter 9
How do information systems help organizations
carry out their missions?

• First, it can become better at what it does by
  cutting costs, lowering prices, improving its
  products, offering better customer service, and
  so on
• A second response is to change the structure of
  an industry
• As a third response, an organization can create a
  new product
• As organizations respond to opportunities and
  threats, they change. It can be important to
  understand the nature of coming changes

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Information Systems
Section A
Chapter 9
How do information systems help organizations
carry out their missions?
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Information Systems
Section A
Chapter 9
Do organizations require different kinds of
information systems?

• Because organizations have different missions,
  face different threats, and encounter different
  opportunities, they require different kinds of
  information systems

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Information Systems
Section A
Chapter 9
Office Automation Systems Can an information
system automate routine office tasks?

• An office automation system automates, or
  computerizes, routine office tasks
• Office automation systems can be used by workers
  and managers at all levels of the organizational
  hierarchy

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Information Systems
Section A
Chapter 9
Transaction Processing Systems Whats a
transaction?

• A transaction is an exchange between two parties
  that is recorded and stored in a computer system

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Information Systems
Section A
Chapter 9
What is a transaction processing system?

• A transaction processing system (TPS) provides a
  way to collect, process, store, display, modify,
  or cancel transactions
• Early transaction processing systems used batch
  processing to collect and hold a group of
  transactions for processing until the end of a
  day or pay period
• Most modern transaction processing systems use
  online processing. Such systems are often
  referred to as OLTPS (online transaction
  processing systems)

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Information Systems
Section A
Chapter 9
What is a transaction processing system?

• A TPS can commit to a transaction and permanently
  update database records only if every step of the
  transaction can be successfully processed
• If even one step fails, however, the entire
  transaction fails and the records must roll back
  to their original state

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Information Systems
Section A
Chapter 9
What is a transaction processing system?
Click to start
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Information Systems
Section A
Chapter 9
What are common examples of transaction
processing systems?

• A point-of-sale (POS) system records items
  purchased at each cash register, and calculates
  the total amount due for each sale
• An order-entry/invoice system provides a way to
  input, view, modify, and delete customer orders
• A general accounting system records the financial
  status of a business by keeping track of income,
  expenses, and assets
• An e-commerce system collects orders and
  processes credit card payments

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Information Systems
Section A
Chapter 9
What are the limitations of transaction
processing systems?

• Most transaction processing systems reporting
  capabilities are limited
• Managers need more sophisticated reports to help
  them understand and analyze data

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Information Systems
Section A
Chapter 9
Management Information Systems What is a
management information system?

• A management information system (MIS, pronounced
  EM EYE ESS) refers to a type of information
  system that uses the data collected by a
  transaction processing system, but manipulates
  that data to create reports that managers can use
  to make routine business decisions in response to
  structured problems

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Information Systems
Section A
Chapter 9
What is a management information system?
Click to start
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Information Systems
Section A
Chapter 9
What is a management information system?

• One of the major goals of an MIS is to increase
  the efficiency of managerial activity
• A summary report combines or groups data and
  often shows totals
• An exception report contains information that is
  outside of normal or acceptable ranges
• Scheduled reports follow a fixed format and are
  produced according to a preset timetable
• An ad hoc report is a customized report,
  generated to supply specific information not
  available in scheduled reports

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Information Systems
Section A
Chapter 9
What is a management information system?
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Information Systems
Section A
Chapter 9
How does an MIS differ from a TPS?

• Whereas a TPS simply records data, an MIS can
  consolidate data by grouping and summarizing it

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Information Systems
Section A
Chapter 9
What are the limitations of a management
information system?

• A traditional MIS is based on the data collected
  by a transaction processing system
• The reports generated by an MIS are limited by
  the processing capabilities of the database
  software.
• The MIS cannot typically be used to create models
  or projections

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Information Systems
Section A
Chapter 9
Decision Support Systems Whats a decision
support system?

• A decision support system (DSS) helps people make
  decisions by directly manipulating data,
  analyzing data from external sources, generating
  statistical projections, and creating data models
  of various scenarios
• A special type of decision support system, called
  an executive information system (EIS), is
  designed to provide senior managers with
  information relevant to strategic management
  activities based on information provided by the
  organizations database

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Information Systems
Section A
Chapter 9
Whats a decision support system?

• A DSS does not make decisions, however. That
  task remains the responsibility of the human
  decision maker
• A decision model is a numerical representation of
  a realistic situation
• A decision query is a question or set of
  instructions describing data that must be
  gathered to make a decision
• A DSS typically includes modeling tools so
  managers can create a numerical representation of
  a situation and explore what-if alternatives

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Information Systems
Section A
Chapter 9
Whats a decision support system?
Click to start
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Information Systems
Section A
Chapter 9
What kinds of decisions can a DSS handle?

• A DSS can be used to tackle diverse problems
  because it contains a good selection of decision
  support tools

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Information Systems
Section A
Chapter 9
What are the limitations of a DSS?

• A DSS helps people manipulate the data necessary
  to make a decision, but does not actually make a
  decision
• A DSS is appropriate in situations where it is
  used by trained professionals

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Information Systems
Section A
Chapter 9
Expert Systems and Neural Networks What is an
expert system?

• An expert system, sometimes referred to as a
  knowledge-based system, is a computer system
  designed to analyze data and produce a
  recommendation, diagnosis, or decision based on a
  set of facts and rules
• The facts and rules for an expert system are
  typically derived by interviewing one or more
  experts, and then incorporated into a knowledge
  base
• The knowledge base is stored in a computer file
  and can be manipulated by software called an
  inference engine

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Information Systems
Section A
Chapter 9
What is an expert system?
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Information Systems
Section A
Chapter 9
What is an expert system?
Click to start
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Information Systems
Section A
Chapter 9
What kinds of decisions can an expert system
make?

• An expert system is not a general-purpose problem
  solver or decision maker
• Each expert system is designed to make decisions
  in a particular area or domain.

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Information Systems
Section A
Chapter 9
How are expert systems built?

• Expert systems can be created with a computer
  programming language or an expert system shell
• An expert system shell is a software tool that
  contains an inference engine and a user interface
  that provides a way to enter facts and rules

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Information Systems
Section A
Chapter 9
Can an expert system deal with uncertainty?

• Using a technique called fuzzy logic, an expert
  system can deal with imprecise data by asking for
  a level of confidence

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Information Systems
Section A
Chapter 9
Is it possible to build an expert system
without an expert?

• An expert system begins with a set of facts and
  rules. But if the rules are not known, an
  computer can learn how to make decisions based
  on hundreds or thousands of lightning-fast trial
  and error attempts
• A neural network uses computer circuitry to
  simulate the way a brain might process
  information, learn, and remember

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Information Systems Analysis and Design
Systems Analysis
Section B
CHAPTER 9
PARSONS/OJA
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Systems Analysis
Section B
Chapter 9
Planning Phase How does an information system
project begin?

• An information system project begins with a
  planning phase
• The goal of these activities is to create a
  Project Development Plan
• This planning document includes
• A short description of the project, including its
  scope
• A justification for the project
• A list of project team participants
• A schedule for the project, including an outline
  of its phases

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Systems Analysis
Section B
Chapter 9
How does an information system project begin?
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Systems Analysis
Section B
Chapter 9
Assemble Project Team Who supervises the
development project?

• An Information Systems department, or IS
  department, is the wing of a business or
  organization responsible for developing and
  maintaining the computers, data, and programs for
  an information system
• Some organizations refer to the IS department as
  the IT (Information Technology) department or MIS
  (Management Information Systems) department

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Systems Analysis
Section B
Chapter 9
Who supervises the development project?

• Most IS departments are headed by a chief
  information officer (CIO)
• A computer professional called a systems analyst
  is responsible for analyzing information
  requirements, designing new information systems,
  and supervising their implementation

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Systems Analysis
Section B
Chapter 9
Who participates in the process of building an
information system?

• A system development project team is a group of
  people who are assigned to analyze and develop an
  information system
• In addition to the project team, other members of
  the organization might be asked to participate
• A widely accepted technique called joint
  application design (JAD) is based on the idea
  that the best information systems are designed
  when end users and systems analysts work together
  on a project as equal partners

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Systems Analysis
Section B
Chapter 9
Justify Project Why are new information
systems developed?

• The justification for a new information system
  usually emerges from a serious problem with the
  current system, or from an opportunity to improve
  an organizations products or services using
  technology

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Systems Analysis
Section B
Chapter 9
Why are new information systems developed?
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Systems Analysis
Section B
Chapter 9
System Development Life Cycle How does the
project team know what to do?

• The project team typically proceeds according to
  a system development methodology chosen by the IS
  department

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Systems Analysis
Section B
Chapter 9
What is a system development life cycle?
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Systems Analysis
Section B
Chapter 9
What is a system development life cycle?

• A system development life cycle (SDLC) an outline
  of a process that helps develop successful
  information systems
• The original waterfall SDLC approaches each phase
  as a discrete step in the development process
• A modified waterfall SDLC allows overlap between
  SDLC phases.
• An iterative SDLC allows phases to repeat, if
  necessary, as the project progresses

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Systems Analysis
Section B
Chapter 9
What is a system development life cycle?
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Systems Analysis
Section B
Chapter 9
How do different SDLCs affect project
development?

• The structured methodology focuses on the
  processes that take place within an information
  system
• The information engineering methodology focuses
  on the data that an information system collects
  before working out ways to process that data
• The object-oriented methodology treats an
  information system as a collection of objects
  that interact with each other to accomplish tasks

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Systems Analysis
Section B
Chapter 9
How do different SDLCs affect project
development?

• A methodology called rapid application
  development (RAD) proceeds with the project team
  creating a series of prototypes that users can
  evaluate
• Different SDLCs also affect the project schedule
• The tools for analyzing and designing an
  information system are directly related to the
  methodology

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Systems Analysis
Section B
Chapter 9
Analysis Phase What happens in the analysis
phase?

• The goal of the analysis phase is to produce a
  list of requirements for a new or revised
  information system

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Systems Analysis
Section B
Chapter 9
Study the Current System Is it really
important to understand the current system before
planning a new system?
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Systems Analysis
Section B
Chapter 9
Is it really important to understand the
current system before planning a new system?

• Typically, a new information system is designed
  to replace a system or process that is already in
  place
• It is important to study the current system to
  understand its strengths and weaknesses before
  planning a new system

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Systems Analysis
Section B
Chapter 9
How does the project team discover what happens
in the current system?

• Some members of the project team might have
  first-hand experience with the current system
• They can often provide an overview of the system
• To obtain additional information about the
  current system, the project team members can
  interview the people who use the system, or
  observe the system in action

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Systems Analysis
Section B
Chapter 9
Determine System Requirements How does the
project team determine what the new system should
do?

• System requirements are the criteria for
  successfully solving the problem or problems
  identified in an information system
• They also serve as an evaluation checklist at the
  end of the development project, so they are
  sometimes called success factors

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Systems Analysis
Section B
Chapter 9
How does the project team document system
requirements?

• The project team can use a variety of tools to
  diagram the current system and specify what it
  does
• It can be difficult, however, to maintain this
  documentation as the project progresses
• A CASE tool (computer-aided software engineering
  tool) is a software application that is designed
  for documenting system requirements, diagramming
  current and proposed information systems,
  scheduling development tasks, and developing
  computer programs

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Systems Analysis
Section B
Chapter 9
How does the project team document system
requirements?
Click to start
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Systems Analysis
Section B
Chapter 9
What marks the end of the analysis phase of the
SDLC?

• The analysis phase concludes when the project
  team produces a written report that documents its
  findings
• The System Requirements Report typically contains
  diagrams that illustrate what the new information
  system should do

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Information Systems Analysis and Design
Systems Design
Section C
CHAPTER 9
PARSONS/OJA
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System Design
Section C
Chapter 9
Design Phase What happens in the design phase?

• In the design phase of the SDLC, the project team
  must figure out HOW the new system will fulfill
  the requirements specified in the System
  Requirements Report

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System Design
Section C
Chapter 9
Identify Potential Solutions How does the
project team come up with solutions?

• There might be more than one way to solve the
  problems and meet the requirements identified in
  the analysis phase of the SDLC
• The project team should identify several
  potential hardware and software solutions by
  brainstorming and researching case studies on
  Web sites and in computer magazines

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System Design
Section C
Chapter 9
What kinds of hardware alternatives are
available?

• A myriad of hardware options are available for
  information systems
• Mainframes, servers, and personal computers are
  the most commonly used components, but in some
  information systems, handhelds, or even
  supercomputers, play a role

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System Design
Section C
Chapter 9
What level of automation and computerization
will be required?

• The project team should consider the pros and
  cons of different levels
• Centralized or distributed processing
• Centralized processing is when data is processed
  on a centrally located computer
• Distributed processing is when processing tasks
  are distributed to servers and workstations
• Network technology

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System Design
Section C
Chapter 9
What level of automation and computerization
will be required?
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System Design
Section C
Chapter 9
What kinds of software alternatives are
available?

• The project team might consider software
  alternatives, such as whether to construct the
  system from scratch, use an application
  development tool, or commercial software
• Creating an information system from scratch
  using a programming language can take many months
  or years
• An application development tool is essentially a
  type of software construction kit containing
  building blocks that can be assembled into a
  software product

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System Design
Section C
Chapter 9
What kinds of software alternatives are
available?

• Commercial software for an information system is
  usually a series of pre-programmed software
  modules, supplied by a software developer,
  consulting company, or value-added reseller (VAR)
• A turnkey system is essentially an information
  system in a box which consists of hardware and
  commercial software designed to offer a complete
  information system solution
• A turnkey system must be extensively evaluated to
  determine whether it can satisfy system
  requirements

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System Design
Section C
Chapter 9
Evaluate Solutions and Select the Best How
does the team choose the best solution?

• To determine the best solution the project team
  devises a list of criteria for comparing each of
  the potential solutions
• Each criterion is assigned a weight to indicate
  its importance. The project team then evaluates
  the criteria for each solution and assigns raw
  scores
• Sound complicated? It isnt, especially if the
  project team uses a decision support worksheet

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System Design
Section C
Chapter 9
How does the team choose the best solution?
Raw scores indicate how well each solution meets
each criterion.
The highest weights indicate the most important
criteria.
A list of criteria includes features and factors
that are important to the success of the
information system.
A weighted score is obtained by multiplying the
weight by the raw score.
The solution with the highest total is the best
choice.
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System Design
Section C
Chapter 9
Select Hardware and Software How does the
project team find the right hardware and software
for the new information system?

• Once the project team selects a solution, the
  next task is to select the hardware and software
  needed to implement the solution
• The method for selecting the hardware, software,
  and vendor depends on the project teams
  understanding of what is required for the solution

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System Design
Section C
Chapter 9
Whats an RFP?

• A request for proposal (RFP) is a document that
  describes the information system problem and the
  requirements for the solution

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System Design
Section C
Chapter 9
Whats an RFQ?

• A request for quotation (RFQ) is a request for a
  formal price quotation on a list of hardware and
  software

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System Design
Section C
Chapter 9
How does the project team evaluate an RFP or
RFQ?

• The project team can evaluate RFPs or RFQs by
  constructing a decision table similar to the one
  used for evaluating solutions

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System Design
Section C
Chapter 9
Develop Application Specifications What
happens after the project team selects a solution?

• Exactly what happens next in the system design
  phase depends on the type of solution selected
• If the project team selected a solution that
  requires custom programming, the teams systems
  analysts will create a set of application
  specifications

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System Design
Section C
Chapter 9
What happens after the project team selects a
solution?
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System Design
Section C
Chapter 9
Why werent the specifications developed as
part of the requirements report?

• Detailed application specifications can be
  developed only after the hardware and software
  for an information system are selected

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System Design
Section C
Chapter 9
What happens to the completed specifications?

• Application specifications are similar to the
  pages of an architectural blueprint that show the
  detailed plan for electrical wiring or plumbing
• In a large information systems project, the
  specifications are given to a programming team or
  application developer who creates the software
• In a small information systems project, you as
  the user might develop your own specifications

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System Design
Section C
Chapter 9
Obtain Approval to Implement the New System
When can the project team actually begin to build
the new information system?

• In the design phase of the SDLC, the project team
  chooses a solution, selects hardware and
  software, and designs detailed application
  specifications
• Before the solution is implemented, the project
  team typically must seek approval from management

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Information Systems Analysis and Design
Implementation and Maintenance
Section D
CHAPTER 9
PARSONS/OJA
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Implementation and Maintenance
Section D
Chapter 9
Implementation Phase What happens during the
implementation phase?

• During the implementation phase of the SDLC, the
  project team supervises the tasks necessary to
  construct the new information system

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Implementation and Maintenance
Section D
Chapter 9
Purchase and Install Hardware and Software
Does a new information system typically require
new hardware?

• Most new information systems require new
  hardware, which can either replace old equipment,
  or be connected to existing equipment

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Implementation and Maintenance
Section D
Chapter 9
How about new software?

• Many information systems require new software,
  such as a commercial application, a programming
  language, an application development tool, or an
  expert system shell

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Implementation and Maintenance
Section D
Chapter 9
Create Applications After the project team
installs the new hardware and software, whats
the next step in the implementation phase?

• The next step in the implementation phase depends
  on the software tools selected for the project
• Software customization is the process of
  modifying a commercial application to reflect the
  needs of a particular organization
• The process of designing, entering, and testing
  the rules in an expert system is referred to as
  knowledge engineering

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Implementation and Maintenance
Section D
Chapter 9
Test Applications How can the team ensure that
a new information system works?

• A rigorous testing process is the only way to
  make sure that a new information system works

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Implementation and Maintenance
Section D
Chapter 9
What is application testing?

• Application testing is the process of trying out
  various sequences of input values and checking
  the results to verify that the application works
  correctly
• As each application module is completed, it
  undergoes unit testing to ensure that it operates
  reliably and correctly
• When all modules have been completed and tested,
  integration testing is performed to ensure that
  the modules operate together correctly

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Implementation and Maintenance
Section D
Chapter 9
What is application testing?

• A test area is a place where software testing can
  occur without disrupting the organizations
  regular information system
• When a problem is discovered during unit testing
  or integration testing, the team must track down
  the source of the problem and correct it
• System testing ensures that all hardware and
  software components work together correctly

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Implementation and Maintenance
Section D
Chapter 9
Finalize Documentation What is the
documentation for an information system?

• The documentation for an information system can
  be roughly categorized as system or user
  documentation
• System documentation describes the feature of the
  system
• User documentation describes how to interact with
  the system to accomplish specific tasks

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Implementation and Maintenance
Section D
Chapter 9
Train Users How do employees learn how to use
the new information system?

• In preparation for using a new information
  system, users need extensive training, which
  might include software orientation, hardware
  operation, data entry, and backup procedures
• Training sessions can be conducted by members of
  the team or professional trainers
• A procedure handbook is a type of user
  documentation that contains step-by-step
  instructions for performing a specific task

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Implementation and Maintenance
Section D
Chapter 9
Convert Data What happens to the data from the
old system?

• The data for a new information system might exist
  in card files, file folders, or an old
  information system
• When converting data from a manual system to a
  computer system, the data can be typed or scanned
  electronically into the appropriate storage media
• When converting data from an existing computer
  system to a new system, a programmer typically
  writes conversion software to read the old data
  and convert it into a format that is usable by
  the new system

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Covert to New System How does a business
switch from the old information system to the new
system?

• System conversion refers to the process of
  deactivating an old information system and
  activating the new one
• A direct conversion means that the old system is
  completely deactivated and the new system is
  immediately activated
• A parallel conversion avoids some of the risk
  because the old system remains in service while
  some or all of the new system is activated
• In a phased conversion, the new system is
  activated one module at a time

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How does a business switch from the old system
to the new system?

• A pilot conversion works well in organizations
  with several branches that have independent
  information processing systems
• The new information system is activated at one
  branch
• If the system works correctly at one branch, it
  is activated at the next branch

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When is the new information system formally
live?

• A new or upgraded information system undergoes a
  final test called acceptance testing
• Acceptance testing is designed to verify that the
  new information system works as required

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Maintenance Phase What happens during the
maintenance phase?

• The maintenance phase of the SDLC involves
  day-to-day operation of the system, making
  modifications to improve performance, and
  correcting problems
• The maintenance phase of the SDLC is the most
  expensive because it lasts until the system is
  retired

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What happens during the maintenance phase?
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Who is responsible for system maintenance?

• The system operator performs system backups and
  data recovery, monitors system traffic, and
  troubleshoots operational problems
• The systems programmer is the operating system
  guru
• In an information system that is centered on a
  microcomputer network, a network manager or
  network specialist is typically responsible for
  day-to-day operations and system maintenance

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Why do maintenance activities include user
support?

• Even after-in-depth training, employees sometimes
  forget procedures, or have difficulty when they
  encounter a new set of circumstances
• Many organizations establish a help desk to
  handle end-user problems
• The help desk is staffed by support specialists

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Why do maintenance activities include user
support?
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Does an information system change during the
maintenance phase?

• The term maintenance phase is a bit misleading
• Changes during the maintenance phase typically
  include the following
• Upgrades to operating system and commercial
  software
• User interface revisions
• Application software revisions
• Hardware replacements
• Security upgrades

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When does the maintenance phase end?

• The maintenance phase continues until an
  information system is no longer cost effective,
  or until changes in the organization make the
  information system obsolete

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