Systems Analysis & Design Introduction

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Karolina Muszyńska
Based on http://www.csun.edu/~dn58412/IS431/IS431_SP13.html
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Information systems in organization
Information systems and their stakeholders
Role of system analysts
IS building blocks – focuses for information
systems
System development process overview
Principles of system development
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Information System (IS): People, data, processes,
and information technology that interact to
collect, process, store, and provide as output the
information needed to support and improve
operational, tactical, and strategic activities of an
organization (business).
Information Technology (IT): A combination of
computer technology (hardware and software)
with telecommunications technology (data,
image, and voice networks)
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Information Systems in Organization
STRATEGIC
EXECUTIVE INFORMATION SYSTEMS
TACTICAL
MANAGEMENT INFORMATION SYSTEMS
TRANSACTION PROCESSING SYSTEMS
OPERATIONAL
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VALUE CHAIN
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Transaction Processing Systems
Management Information Systems
Executive Information Systems
Decision Support Systems
Expert Systems
Functional Area Information Systems
(Accounting, HR, Sales, Production …)
Office Automation Systems (Personal Productivity
Software)
Collaboration Systems (Groupware)
Enterprise Systems
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Information System in Context
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Stakeholder: any person who has an interest in an
existing or proposed information system.
Stakeholders can be technical or nontechnical
workers. They may also include both internal and
external workers.
Information workers are those workers whose jobs
involve the creation, collection, processing,
distribution, and use of information.
Knowledge workers are a subset of information
workers whose responsibilities are based on a
specialized body of knowledge.
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Perspectives on an Information System
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System owners – an information system’s
sponsors and executives advocate, usually
responsible for funding the project of
developing, operating, and maintaining the
information system. They define the SCOPE
of a system: what business problem is to be
solved
◦ They view the system in terms of cost/benefit to
solve business problem
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System Users
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System users – use or are affected by an
information system on a regular basis –
capturing, validating, entering, responding to,
storing, and exchanging data and information.
They define the REQUIREMENTS of the system.
◦ Internal users
 Clerical and service workers
 Technical and professional staff
 Supervisors, middle managers, and executive managers
 Remote and mobile users (internal but disconnected)
◦ External users
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System designers translate system users’
business requirements and constraints into
technical solution: computer databases, inputs,
outputs, networks, and software meeting the
system users’ requirements. Their activities
relate to the DESIGN of a system
System builders construct information systems
based on the design specifications from the
system designers. Their activities relate to
building the COMPONENTS of the system.
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Systems analysts study the problems and needs
of an organization to determine how people,
data, processes, and information technology can
best accomplish improvements for the business.
They are FACILITATORS of the system
development project.
• A programmer/analyst (or analyst/programmer)
includes the responsibilities of both the computer
programmer and the systems analyst.
• A business analyst focuses on only the nontechnical
aspects of systems analysis and design.
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What “problems” to solve: (Project Definition)
◦ True problem situations, either real or anticipated, that
require corrective action
◦ Opportunities to improve a situation despite the absence of
complaints
◦ Directives to change a situation regardless of whether
anyone has complained about the current situation
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Why: (Project Justification)
◦ Effective: Do right thing
◦ Efficient: Do thing right
◦ Competitive: Do thing differently
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Working knowledge of information technology
Computer programming experience and expertise
General business knowledge
General problem-solving skills
Good interpersonal communication skills
Good interpersonal relations skills
Flexibility and adaptability
Character and ethics
Systems Analysis and Design Skills
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Information systems architecture - a unifying
framework into which various stakeholders with
different perspectives can organize and view the
fundamental building blocks of information
systems.
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KNOWLEDGE (Data) — the raw material used to create
useful information.
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PROCESSES — the activities (including management) that
carry out the mission of the business.
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COMMUNICATION (Interfaces) — how the system interfaces
with its users and other information systems.
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Problem – an actual undesirable situation
that prevents the organization from fully
achieving its purpose, goals, and/or
objectives.
Opportunity – a chance to improve the
organization even in the absence of an
identified problem.
Directive - a new requirement that is
imposed by management, government, or
some external influence/parties.
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System development process – a set of activities,
methods, best practices, deliverables, and
automated tools that stakeholders use to develop
and continuously improve information systems and
software
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System Development Process Context
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System initiation – the initial planning for a project to
define initial business scope, goals, schedule, and budget.
System analysis – the study of a business problem domain
to recommend improvements and specify the business
requirements and priorities for the solution.
System design – the specification or construction of a
technical, computer-based solution for the business
requirements identified in a system analysis.
System implementation – the construction, installation,
testing, and delivery of a system into production.
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System Building Blocks
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Purpose: define perceived problems,
opportunities, and directives; assess the risk of
project; establish scope, preliminary
requirements and constraints, participants,
budget and schedule (preliminary study)
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Issues: Is the project worthwhile? Define the
scope of project
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Deliverable: Project charter/plan
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Feasibility check: Cancel project / Approve to
continue / Reduce or expanse the scope with
budget and schedule modification
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Purpose: to study and analyze the existing system
from the users’ perspectives as they see Data,
Processes, and Interfaces
Issue: Cost/benefits of building new system to
solve these problems
Deliverable: system improvement objectives
(business criteria to evaluate the new system)
Feasibility check: Cancel project / Approve to
continue / Reduce or expanse the scope with
budget and schedule modification
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Purpose: discover users’ needs or expectations
out of the new system in terms of Data, Processes,
and Interfaces
Issue: Specify requirements for the new system
(WHAT IS TO BE DONE) without prematurely
expressing technical details (HOW)
Errors and omissions in requirement analysis
result in user dissatisfaction of final system and
costly modifications
Deliverable: business requirements statement
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Purpose: translating business user requirements
into a system model that depicts only WHAT TO
DO without specifying any possible technical
design or implementation of those requirements
(conceptual design).
Issue: using graphical model of a system to
represent user requirements in terms of Data,
Processes and Interfaces, and to facilitate
improved communication between system
stakeholders.
Deliverable: Logical Systems Models (DFD, ERD,
Use Case Diagrams, Class Diagrams, etc.)
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Purpose: identify all candidate solutions, analyze
the feasibility of each candidate, recommend a
candidate system as the target solution
Issue: Feasibility analysis in terms of technical,
operational, economic, schedule (TOES), and risk
Deliverable: approved system proposal
Feasibility check: Cancel project / Approve
system proposal with budget and schedule
modification / Reduce the scope of proposed
solution with budget and schedule modification
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Candidate solutions evaluated in terms of TOES
and Risks:
◦ Technical feasibility – Is the solution technically practical? Does
our staff have the technical expertise to design and build this
solution?
◦ Operational feasibility – Will the solution fulfill the users’
requirements? To what degree? How will the solution change
the users’ work environment? How do users feel about such a
solution?
◦ Economic feasibility – Is the solution cost-effective?
◦ Schedule feasibility – Can the solution be designed and
implemented within an acceptable time?
◦ Risk feasibility – What is the probability of a successful
implementation using the technology and approach? (Risk
Management)
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Purpose: to transform business requirements
into technical design specifications for
construction
Issue: HOW technology will be used to build the
system in terms of Data, Processes, and
Interfaces
Design by Specifications vs. Design by
Prototyping
Deliverable: System design specifications
Feasibility check: Continue/ Reduce or expanse
the scope with budget and schedule modification
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Purpose: to build and test a system that fulfills
business requirements and design specs;
implement interfaces between new and existing
systems
Issue: Construct database, application programs,
user/system interfaces, implement software
Deliverable: proposed system within budget and
schedule
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Purpose: deliver the production system into
operation
Issue: Train users, write manuals, load files,
populate database, final test
Conversion plan: parallel systems, switch point
Deliverable: system up and running
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Ongoing system support would be provided until
the system becomes obsolete and is replaced by
a new one
Issues: technical support for user, fixing bugs,
recovering plan, adapt to emerging requirements
When a system has reached entropy, new project
for new system should be initiated
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Scope Definition Phase: What Business Problem
Problem Analysis Phase: What System Issues
(Info/Data, Processes, Communications/Interfaces)
Requirement Analysis Phase: What User Needs
Logical Design: Conceptual Model – What to Do
Decision Analysis Phase: What Solution
Design Phase: Physical Model: How to Do
Construction Phase: Do It
Implementation Phase: Use It
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Cross life-cycle activity – any activity that overlaps many or all
phases of the systems development process.
◦ Fact-finding - the formal process of using research, interviews,
meetings, questionnaires, sampling, and other techniques to
collect information about system problems, requirements and
preferences.
◦ Documentation and presentation
 Documentation – the ongoing activity of recording facts and
specifications for a systems for current and future reference.
 Presentation – the ongoing activity of communicating findings,
recommendations, and documentation for review by interested
users and mangers.
 Repository – a database and/or file directory where system
developers store all documentation, knowledge, and artifacts
for one or more information systems or projects.
◦ Feasibility analysis
◦ Process and project management
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Principles of System Development
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Get the system users involved
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Use a problem-solving approach
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Establish phases and activities
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Document throughout the development
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Establish standards
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Manage the process and projects
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Justify systems as capital investments
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Don’t be afraid to cancel or revise scope
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Divide and conquer
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Design systems for growth and change
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Principle 1: Get the owners and users involved
in all system development phases.
User Participation/Involvement creates “System
Ownership” and leads to User Acceptance and
User Satisfaction.
Bottom line: owners and users will live with the
system !!!
“OUR system [owners + users + developers] will
be effective, efficient, competitive, user
friendly”
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Principle 2: Use a problem solving approach
◦ Study and understand the problem in its context
◦ Define the requirements of a suitable solution
◦ Identify candidate solutions and select the best
available
◦ Design and/or implement the solution
◦ Observe and evaluate the solution impact, and
refine the solution accordingly
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Principle 3: Establish phases and activities
(define a process to follow)
◦ Scope definition
◦ Problem Analysis
◦ Requirement Analysis
◦ Logical Design
◦ Decision Analysis
◦ Physical Design and Integration
◦ Construction and Testing
◦ Implementation and Delivery
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These phases identify problems, evaluate,
design, and implement solution (Systems
Development Process)
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Principle 4: Document throughout the
system development process
◦ Ongoing activity to reveal strength and
weakness of the system during the
development process
◦ Enhance communication and acceptance
among stakeholders
◦ Agreements and Contracts between
Owner/User and Analyst/Designer on the
Scope, Requirements, Resources of the project.
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Principles of System Development …
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Principle 5: Establish standards for
consistency
◦ System development standards: documentation,
methodology
◦ Business standards: business rules and
practices
◦ IT standards : common architecture and
configuration for a consistent system
development
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Principle 6: Manage the process and projects
◦ Process management : ongoing activity that
documents, manages, oversees the use of, and
improves an organization’s chosen methodology (the
“process”) for system development. Process
management is concerned with phases, activities,
deliverables, and quality standards should be
consistently applied to all projects.
◦ Project management : the process of scoping,
planning, staffing, organizing, directing, and
controlling a project to develop an information
system at a minimum cost, within a specified time
frame, and with acceptable quality.
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Principles of System Development …
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Principle 7: Justify Systems as Capital
Investments
◦ Strategic Information System Plan fits in and
supports Strategic Enterprise Plan
◦ There are several possible solutions, the first
one is not necessary the best
◦ Feasibility of each solution in terms of
 Cost Effectiveness: Cost/benefit analysis
 Risk management: Identification,
evaluation, and control of potential threat
to the completion of a system
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Principle 8: Don’t be Afraid to Cancel and
Revise Scope: Creeping Commitment
◦ Expectation and scope of a project may be growing
up
◦ Development process has checkpoints for its phases:
all costs committed so far are sunk costs.
 Cancel the project if it is no longer feasible
(ORGANIZATION)
 Reevaluate/adjust cost/schedule if the scope is
expanding (ANALYST)
 Reduce the scope if budget/schedule is shrinking
(ANALYST)
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Principle 9: Divide and Conquer
◦ Divide a complex system into simpler
subsystems/components
◦ Problem solving process could be simplified for
smaller problems
◦ Different subsystems for different stakeholders
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Principle 10: Design Systems for Growth and
Change
◦ Changes of technology, user requirements
◦ Flexibility and adaptability should be built into
the system
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