System Analysis Overviewapproaches, phases and requirements discovery

Karolina Muszyńska

Based on http://www.csun.edu/~dn58412/IS431/IS431_SP13.html

Systems Analysis vs. Systems Design Systems Analysis Phases and Tasks User Requirements Discovery Systems Analysis Approaches

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Systems Analysis Overview

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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

Scope Definition Phase – WHAT PROBLEM• Is the project worth looking at to solve problem?

Problem Analysis Phase – WHAT ISSUES• Is a new system worth building?

Requirements Analysis Phase – WHAT REQUIREMENTS• WHAT do the users need and want from the new system?

Logical Design Phase – WHAT TO DO• WHAT must the new system do to satisfy users’ needs?

Decision Analysis Phase – WHAT SOLUTION• WHAT is the best solution among others?

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Classic Systems Analysis Phases

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Scope Definition Phase

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Scope Definition Tasks

Task 1.1: Identify Problems, Opportunities, and Directives◦ Deliverable: Preliminary Problem Statement

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

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1. Scope Definition Tasks…

Task 1.3: Assess Project Worthiness◦ Cost/benefit analysis ◦ Decision: approve, cancel, renegotiate the scope

Task 1.4: Schedule and Budget Plan for Project◦ Deliverables: Project Charter – schedule and resource

assignment Task 1.5: Present the Project and Plan

◦ Deliverable: Project Charter (participants, problems, scope, methodology, statement of work to be completed, deliverables, quality standards, schedule, budget)

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1. Scope Definition Tasks…

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Problem Analysis Phase

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Problem Analysis Tasks

Task 2.1: Study the Problem Domain◦ DATA: currently stored data, their business terms◦ PROCESSES: current business events◦ INTERFACES: current locations and users◦ Deliverable: definition of system domain/models of

Current System Task 2.2: Analyze Problems and Opportunities

◦ Deliverables: updated problem statements and the cause-effect analyses for each problem and opportunities

Task 2.3: Analyze Business Processes◦ Deliverable: current business process models

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2. Problem Analysis Tasks…

Task 2.4: Establish System Improvement Objectives◦ Deliverable: System Improvement Objectives and

Recommendations Report Task 2.5: : Update the Project Plan

◦ Deliverable: updated project plan Task 2.6: Present Findings and

Recommendations◦ Deliverable: system improvement objectives◦ Decision: continue/adjust/cancel current project

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2. Problem Analysis Tasks…

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Requirements Analysis Phase

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Requirements Analysis Tasks

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3. Requirements Analysis Tasks Task 3.1: Identify System Requirements

◦ Functional requirements: activities and services provided 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 Tasks 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.

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 Design Tasks Task 4.1: Analyze Functional Requirements

◦ Logical systems models: WHAT the system must do (not HOW)

◦ 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

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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Decision Analysis Phase

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Decision Analysis Tasks

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5. Decision Analysis Tasks Task 5.1: Identify Candidate Solutions

o Deliverable: candidate systems (solutions) matrix

Task 5.2: Analyze Candidate Solutionso 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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5. Decision Analysis Tasks Task 5.3: Compare Candidate Solutions

o Deliverable: recommended solution Task 5.4: Update the Project Plan

o Review and update the latest project schedule and resource assignments

o Deliverable: updated project plan Task 5.5: Recommend a Solution

Deliverable: System Proposal

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 operation, 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 of 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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Results of Incorrect 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

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Criteria to Define System Requirements

Problem discovery and analysis Requirements discovery Documenting and analyzing requirements Requirements management to handle

changes

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The Process of Requirements Discovery

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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Analyzing 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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Documenting Requirements

Sampling of existing documentation, forms, and databases.

Research and site visits. Observation of the work environment. Questionnaires. Interviews. Discovery Prototyping. Joint requirements planning (JRP) / Joint

application development (JAD)

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Fact-Finding Methods

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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Joint Requirements Planning

Model-driven Analysis• Structured analysis• Information engineering• Object-oriented analysis

Accelerated Systems Analysis• Discovery prototyping• Rapid Architected Analysis

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Systems Analysis Approaches

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 Analysis

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Model-Driven Methods Structured Analysis: a 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

Information Engineering (IE): a DATA-centered, but process-sensitive technique to plan, analyze, and design information systems. IE illustrate and synchronize the system’s data and processes.

Object-oriented Analysis (OOA): a 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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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

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Discovery Prototyping Discovery Prototyping – a technique used to

identify the users’ business requirements by building a small-scale, representative or working model of the users’ requirements in order to discover or verify them.

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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Rapid Architected Analysis Rapid Architected Analysis – derive system

models from existing systems or discovery prototypes.

Reverse Engineering – the use of technology that reads the program code for an existing database, application program, and/or user interface and automatically generates the equivalent system model.