INT1IS Information Systems
Week 4 Lecture 1

Phase 1 - Systems Analysis

also known as

Establish User Requirements

(S.C.& R ch.3)

That is: We need to specify what a user requires for an information processing system before we can design and develop it.

In order to do this we need to ...

1. Fully understand the current system.
2. Reduce the current system to its essentials.
3. Understand the user's requirements for the proposed system.
4. Incorporate the user's requirements for the proposed system into the essential details of the current system.
5. Define which areas of the proposed system can be computerised.
6. State the conditions for acceptance of the proposed system.

Result of the Systems Analysis phase is:

SYSTEMS REQUIREMENTS DOCUMENT

which contains:

1. outline of problem(s)
2. description of current system
3. outline of solution requirements
4. evaluation of alternative solutions
5. recommended alternative including time/costs

Tools used in this document:

1. Unified Modelling Language or Data Flow Diagrams (useful but a bit dated).
2. System Dictionary.
3. Data Base description.
4. Performance targets.
5. Constraints on the system.

... and is essentially graphical and very structured.

What is meant by an Information System's Requirements?

"Specifications of the system to make it understandable and acceptable to the end user."

Five broad categories:

1. Outputs
   eg: alphabetical listing of students for each tutorial
2. Inputs
   eg: students's tutorial selection
3. Processes
   eg: student's record is retrievable by id or student name
4. Timings
   eg: reports and results of inquiries:
     - user initiated?
     - automatic, say after entry of results?
     - automatic at a particular period?
5. Controls
   eg: access to student's records should be controlled by username/password

Volume, size and frequency of access of data must also be estimated.

Includes:

• file sizes, (number of records)
• report widths, lengths and frequencies,
• response times.

Provide information for the designer to ...

• evaluate hardware alternatives.
• decide on file access methods
• estimate other costs....

Systems Analysis task one:

• understand and be able to describe the current system
• obviously involves finding out how the current system works.
  → Fact Finding techniques

References:

• Shelly, Cashman & Rosenblatt, Systems Analysis and Design, 6th Edition,  Course Technology, 2006.

Copyright © 2006 Brian Retallick

This page last updated on Monday 14 July 2008 by Noel McEwan, La Trobe University, Bendigo