CSUN Information Systems
Systems Analysis & Design
http://www.csun.edu/~dn58412/IS431/IS431_SP16.htm
System
Analysis
Overview
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Systems Analysis
Overview
 Systems Analysis vs. Systems Design
 Systems Analysis Approaches
 Systems Analysis Phases (purposes,
participants, inputs, outputs, techniques, and
steps)
–
–
–
–
–
Scope Definition
Problem Analysis
Requirements Analysis
Logical Design
Decision Analysis
 User Requirements Discovery
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System Development
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System Analysis
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Systems Analysis vs.
Systems Design
Systems Analysis: development phases in a
project that primarily focus on the business
problems, i.e., WHAT the system must do in terms
of Data, Processes, and Interfaces, independent of
any technology that can or will be used to
implement a solution to that problem.
Systems Design: development phases focus on the
technical construction and implementation of the
system (HOW technology will be used in the
system.)
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Context of System
Analysis
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Model-Driven Analysis
Model-driven Analysis emphasizes the drawing of
graphical system models to document and validate
both existing and/or proposed systems. Ultimately,
the system model becomes the blueprint for
designing and constructing an improved system.
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Model-Driven Methods
Structured Analysis (Waterfall) : a modeldriven, PROCESS-centered technique to analyze
an existing system and define business
requirements for a new system.
The models illustrate the system’s components:
processes (functions, tasks) and their associated
inputs, outputs, and files.
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A Simple Process Model
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Model-Driven Methods…
Information Engineering (IE):a model-driven
and DATA-centered, but process-sensitive (context
specific) technique to plan, analyze, and design
information systems.
IE illustrate and synchronize the system’s data and
processes.
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A Simple Data Model
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Model-Driven Methods…
Object-oriented Analysis (OOA): a model-driven
technique that integrates data and process concerns
into constructs called OBJECTS.
OOA illustrate the system’s objects from various
perspectives such as structure and behavior.
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A Simple Object Model
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Accelerated Systems
Analysis
• Accelerated Systems Analysis approaches
emphasize the construction of prototypes to more
rapidly identify business and user requirements for a
new system.
 Discovery Prototyping
 Rapid Architected Analysis :derive system models from
existing systems or discovery prototypes.
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Discovery Prototyping
 Discovery Prototyping – a technique used to
identify the users’ business requirements by having
them react to a quick-and-dirty implementation of
those requirements.
– Advantages
 Prototypes cater to the “I’ll know what I want when I see it” way
of thinking that is characteristic of many users and managers.
– Disadvantages
 Can become preoccupied with final “look and feel” prematurely
 Can encourage a premature focus on, and commitment to, design
 Users can be misled to believe that the completed system can be
built rapidly using prototyping tools
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Agile Methods
 Agile Method – the integration of various approaches
of systems analysis and design for applications as
deemed appropriate to the problem being solved and
the system being developed.
– Most commercial methodologies do not impose a single
approach (structured analysis, IE, OOA) on systems
analysts.
– Instead, they integrate all popular approaches into a
collection of agile methods.
– System developers are given the flexibility to select from a
variety of tools and techniques to best accomplish the tasks
at hand,
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Agile Methods …
 Agile methodology aims for customer
satisfaction through early and continuous
delivery of useful application software
components developed by an iterative process
using the bare minimum requirements
 Iterative development – Consists of a series of
tiny projects
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Extreme Programming
 Extreme Programming (XP) – Breaks a project
into tiny phases, and developers cannot continue on
to the next phase until the first phase is complete
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Rational Unified Process
(RUP)
 Rational Unified Process (RUP) – Provides a
framework for breaking down the development
of software into four gates
– Gate One: Inception
– Gate Two: Elaboration
– Gate Three: Construction
– Gate Four: Transition
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SCRUM
 SCRUM – Uses small teams to produce small
pieces of deliverable software using sprints, or 30day intervals, to achieve an appointed goal
 Under this methodology, each day ends or begins
with a stand-up meeting to monitor and control the
development effort
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Classic Systems
Analysis Phases
 Scope Definition Phase
– Is the project worth looking at, for WHAT?
 Problem Analysis Phase
– Is a new system worth building, for WHAT?
 Requirements Analysis Phase
– WHAT do the users need and want from the new system?
 Logical Design Phase
– WHAT must the new system do?
 Decision Analysis Phase
– WHAT is the best solution among others?
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Systems Analysis Phases
 Scope Definition Phase : WHAT PROBLEM
– Is the project worth looking at to solve problem?
 Problem Analysis Phase: WHAT ISSUES
– Is the new system worthwhile to build?
 Requirements Analysis Phase: WHAT REQUIREMENTS
– What do users need and want from the new system?
 Logical Design Phase: WHAT TO DO
– What the new system must do to satisfy user’s needs?
 Decision Analysis Phase: WHAT SOLUTION
– What is the best available solution for the business?
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Scope Definition Phase
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Scope Definition Tasks
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1. Scope Definition
Phase
• Task 1.1: Identify Problems, Opportunities, and
Directives (POD)
•Input: Request for System Service (Fig 5.7)
•Deliverable: Preliminary Problem Statement (Fig 5.8)
•Urgency, Visibility, Benefits, Priority, Possible
Solutions
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System Improvement
Objectives
• Objective – a measure of success. It is something
(measurable) that we expect to achieve, if given sufficient
resources.
 Reduce the number of uncollectible customer accounts by 50
percent within the next year.
 Increase by 25 percent the number of loan applications that
can be processed during an eight-hour shift.
 Decrease by 50 percent the time required to reschedule a
production lot when a workstation malfunctions.
• Constraint – something that will limit our flexibility in
defining a solution to our objectives. Essentially, constraints
cannot be changed.




The new system must be operational by April 15.
The new system cannot cost more than $350,000.
The new system must be web-enabled.
The new system must bill customers every 15 days.
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Problem Statement
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1. Scope Definition
Phase ...
• Task 1.2: Negotiate Preliminary Scope
•Deliverable: Statement of Project Scope (boundary of the
project)
•What types of DATA to be studied
•What business PROCESSES to be included
•How the system INTERFACE with users, locations,
and other systems
•Note: if later the scope changes, the budget and schedule
should be changed accordingly
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1. Scope Definition
Phase …
• Task 1.3: Assess Project Worthiness
•“Is this project worth looking at ?”
•Cost/benefit analysis
•Decision
•Approve project
•Cancel project
•Renegotiate the scope of project (with adjusted
budget and schedule)
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1. Scope Definition
Phase …
• Task 1.4: Schedule and Budget Plan for Project
•Deliverables: Project Charter
•Master plan for the whole project: schedule and
resource assignments
•Detail plan and schedule for completing the next
phase
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1. Scope Definition
Phase …
• Task 1.5: Present the Project and Plan
•Present and defend the project and plan before steering
committee
•Formally launch the project and announce the project,
goals, and schedule
•Deliverable: Project Charter (participants, problems,
scope, methodology, statement of work to be completed,
deliverables, quality standards, schedule, budget)
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Problem Analysis Phase
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Problem Analysis Tasks
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2. Problem Analysis
Phase
• Task 2.1: Study the Problem Domain
•Understanding of the problem domain and business
vocabulary
•DATA: currently stored data, their business terms
•PROCESSES: current business events
•INTERFACES: current locations and users
•Deliverables: definition of system domain / models of
Current System
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2. Problem Analysis
Phase …
• Task 2.2: Analyze Problems and Opportunities
•Study causes and effects of each problem (Note: an effect
may be the cause of other problems)
•Deliverables: updated problem statements and the causeeffect analyses for each problem and opportunities (Fig
5.11)
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2. Problem Analysis
Phase …
• Task 2.3: Analyze Business Processes (for BPR)
•Measure the value added or subtracted by each process
as it relates to the total organization
•Volume of throughput, response time, bottlenecks,
cost, value added, consequences of eliminating or
streamline of the process
•Deliverable: current business process models
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2. Problem Analysis
Phase …
• Task 2.4: Establish System Improvement Objectives
•Define specific system improvement objectives and
constraints for each problem
•Objectives to be precise, measurable
•Constraints in terms of schedule, cost, technology, policy
•Deliverable: System Improvement Objectives and
Recommendations Report
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PROBLEMS, OPPORTUNITIES, OBJECTIVES, AND CONSTRAINTS MATRIX
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2. Problem Analysis
Phase …
• Task 2.5: Update the Project Plan
•Update project:
•Reduce the scope to keep only higher priority
objectives to meet a deadline/budget
•Expanse the scope and adjust schedule and budget
accordingly
•Deliverable: updated project plan
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2. Problem Analysis
Phase …
• Task 2.6: Present Findings and Recommendations
•Deliverable: system improvement objectives
•Decision: continue/adjust/cancel current project
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Requirements Analysis
Phase
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Requirements Analysis
Tasks
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3. Requirements
Analysis Phase
• Task 3.1: Identify System Requirements
• Functional requirements: activities and services
providing by a system: business functions, inputs,
outputs, stored data.
• Nonfunctional requirements: features, characteristics
defining a satisfactory system: performance,
documentation, budget, ease of use and learn, cost saving,
time saving, security
•Deliverable: draft functional and nonfunctional
requirements: improvement objectives and related input,
output, processes, stored data to fulfill the objectives
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3. Requirements
Analysis Phase …
• Task 3.2: Prioritize Requirements
• Mandatory vs. desirable requirements
• Time boxing: deliver the system in a set of subsequent
versions in a time frame. The first version satisfies
essential and highest prioritized requirements.
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3. Requirements
Analysis Phase …
• Task 3.3: Update the Project Plan
•If requirements exceed original vision: reduce the scope
or increase the budget
•Deliverable: consolidated system requirements
(completed requirements and priorities)
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Logical Design Phase
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Logical Design Tasks
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4. Logical Modeling
Phase
• Task 4.1: Analyze Functional Requirements
•Logical systems models: WHAT the system must do (not
HOW)
•Separation of business concerns from technical solutions
will help considering many different ways for business
processes improvement and alternative technical solutions
•Build prototypes to establish user interface requirements
•Deliverables: Data models (ERD), Process models
(DFD), Interfaces models (Context diagram, Use case
diagram), Object models (UML diagrams) of the
Proposed System.
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4. Logical Modeling
Phase …
• Task 4.2: Validate Functional Requirements
•Completeness check, revisit, make changes and additions
to system models and prototypes to assure that
requirements are adequately defined.
•Associate nonfunctional requirements with functional
requirements
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Consolidated
Requirements Statement
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Decision Analysis Phase
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Decision Analysis Tasks
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5. Decision Analysis
Phase
• Task 5.1: Identify Candidate Solutions
•Identify all possible candidate solutions
•Deliverable: candidate systems (solutions) matrix (Fig
5.19)
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Candidate Systems Matrix
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Candidate Systems Matrix..
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5. Decision Analysis
Phase …
• Task 5.2: Analyze Candidate Solutions
•Feasibility analysis is performed on each individual
candidate without regard to the feasibility of other
candidates
•Technical, operational, economic, schedule
feasibilities (TOES)
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Feasibility Analyses
 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 period?
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5. Decision Analysis
Phase …
• Task 5.3: Compare Candidate Solutions
•Select the candidate solution having the “best overall”
combination of technical, operational, economic, and
schedule feasibilities
•Feasibility matrix (Fig 5.20)
•Deliverable: recommended solution
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Feasibility Matrix
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5. Decision Analysis
Phase …
• Task 5.4: Update the Project Plan
•Input: recommended solution
•Review and update the latest project schedule and
resource assignments
•Deliverable: updated project plan
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5. Decision Analysis
Phase …
• Task 5.5: Recommend a Solution
•Deliverable: System Proposal
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The Importance of
Requirements Discovery
System requirement (business requirement) is a
description of the needs and desires for an information
system. A requirement may describe functions, features
(attributes), and constraints.
Functional requirements: functions or features that
must be included in an information system in order to
satisfy the business need and be acceptable to the users.
Nonfunctional requirements: features, characteristics,
and attributes of the system as well as any constraints
that may limit the boundaries of the proposed solution.
Use PIECES framework for classification.
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PIECES Classification of
System Requirements
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Results of Incorrect
Requirements
 The system may cost more than projected.
 The system may be delivered later than promised.
 The system may not meet the users’ expectations
and that dissatisfaction may cause them not to use it.
 Once in production, the costs of maintaining and
enhancing the system may be excessively high.
 The system may be unreliable and prone to errors
and downtime.
 The reputation of the IT staff on the team is
tarnished because any failure, regardless of who is
at fault, will be perceived as a mistake by the team.
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Relative Cost
to Fix an Error
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Criteria to Define System
Requirements
 Consistent – requirements are not conflicting or ambiguous.
 Complete – requirements describe all possible system inputs
and responses.
 Feasible – requirements can be satisfied based on the
available resources and constraints.
 Required – requirements are truly needed and fulfill the
purpose of the system.
 Accurate – requirements are stated correctly.
 Traceable – requirements directly map to the functions and
features of the system.
 Verifiable – requirements are defined so they can be
demonstrated during testing.
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The Process of
Requirements Discovery
Problem discovery and analysis
Requirements discovery
Documenting and analyzing requirements
Requirements management to handle changes
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Ishikawa Diagram
The Ishikawa diagram: graphical tool to identify,
explore, and depict problems, causes and effects of
those problems. (Also called a cause-and-effect
diagram or a fishbone diagram.)
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Ishikawa Diagram …
 Four M’s:
– Materials, Machines, Manpower, and Methods
 Four P’s:
– Places, Procedures, Policies, and People
 Four S’s:
– Surroundings, Suppliers, Systems, and Skills
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Context of
Requirements for an
Information System
USER
ORGANIZATION
SYSTEM
TASK
TOOL
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Analyzing
Requirements
 Analyzing requirements to resolve problems of:
–
–
–
–
–
Missing requirements
Conflicting requirements
Infeasible requirements
Overlapping requirements
Ambiguous requirements
 Formalizing requirements
– Requirements definition document
– Communicated to stakeholders or steering body
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Documenting
Requirements
A requirements definition document should consist
of the following:
– The functions and services that the system should provide.
– Nonfunctional requirements including the system’s
features, characteristics, and attributes.
– The constraints that restrict the development of the system
or under which the system must operate.
– Information about other systems that the system must
interface with.
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Requirements
Management
Requirements management - the process of
managing change to the requirements.
– Over the lifetime of the project it is very common for
new requirements to emerge and existing requirements to
change.
– Studies have shown that over the life of a project as much
as 50 percent or more of the requirements will change
before the system is put into production.
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Fact-Finding Methods
Sampling of existing documentation, forms,
and databases.
Research and site visits.
Observation of the work environment.
Questionnaires.
Interviews.
Prototyping.
Joint requirements planning (JRP).
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Discovery Prototyping
Discovery prototyping – the act of building a
small-scale, representative or working model of the
users’ requirements in order to discover or verify
those requirements.
– Advantages
– Disadvantages
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Joint Requirements
Planning
Joint requirements planning (JRP) – a process
whereby highly structured group meetings (having
defined agenda, key representatives) are conducted
for the purpose of analyzing problems and defining
requirements.
– JRP is a subset of a more comprehensive joint application
development or JAD technique that encompasses the
entire systems development process.
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Benefits of JRP
 JRP actively involves users and management in the
development project (encouraging them to take
“ownership” in the project).
 JRP reduces the amount of time required to develop
systems.
 JRP incorporates the benefits of prototyping as a
means for confirming requirements and obtaining
design approvals.
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