Lecture 4

Determining SystemRequirements

SDLCProject Identification

& Selection

Project Initiation& Planning

Analysis**

Logical Design

Physical Design

Implementation

Maintenance

Requirements Determination System requirements

Functional requirements Current and future functions Current and future data Current and future employee jobs

Requirements Structuring Two essential views of the current and

replacement information systems. Both are describing the same system, but in a different way.

Process view: The sequence of data movement & handling operations within the system

Data flow diagrams

Data: The inherent structure of data independent of how or when it is processed

Entity-relation diagrams

Remember to...

Who will you get info from? User Stakeholders

Users Managers

Client Stakeholders Technical Stakeholders

What Information Do You Need?

1. 2. 3.

Traditional Methods for Determining System Requirements

Administering questionnaires Interviewing and listening Interviewing groups Directly observing users Analyzing procedures & other

documents

Administering QuestionnairesAdvantages & Disadvantages Strengths

1. 2. 3.

Weaknesses 1. 2. 3.

Give Me Ambiguity or Give Me Something Else! How often do you back up your

computer files? A. Frequently B. Sometimes C. Hardly at all D. Never

This is better… How often do you back up the

computer files stored on the hard disk on the PC you use for over 50% of your work time? A. Frequently (at least once per week) B. Sometimes (from 1 to 3 times per

month) C. Hardly at all (once per month or less) D. Never

Interviewing & Listening

Before During the interview Afterwards

During the Interview Beginning

Introduction, open-ended questions, interest & attention

Middle Open & close-ended questions, f-u

questions, active listening, provide feedback, limit note-taking

End Summarize, request feedback and/or f-u,

ask for corrections

InterviewsAdvantages & Disadvantages Strengths

Extracts both qualitative and quantitative data

Detailed and summary data

Good way to find needs and assumptions

Weaknesses Requires skills May be biased;

May collect lots of useless data

Expensive, time consuming

Requires other methods to verify results

How do you choose interview questions?

Open-ended questions 1. 2. 3.

Closed-ended questions 1. 2. 3.

Find out about someone’s job

Write 3 open-ended questions

Ask 3 open-ended questions (You may substitute questions during interview.)

Write down answers

Write 3 closed-ended questions

Ask 3 closed-ended questions (You may substitute questions during interview.)

Write down answers

Interviewing Groups Adv & Disadv Strengths

Not biased by one user’s opinion

Can get many user’s opinion

Weaknesses With many people

present, decision-making takes time

Interruptions during process

You May Need to Analyze Work Procedures Work procedures describe a

particular job or task May show duplication of effort May find missing steps May contradict info collected from

interviews, questionnaires, and observations

Formal systems vs informal systems

Directly ObservingUsers Strengths

Doesn’t rely on a user’s memory

More objective and accurate than interviews

Weaknesses Hawthorne effect Time consuming

Temporary Job Assignment Strengths

Good for learning context, terminology, procedures

Provides insight for other questions

Get operation “feel”; adds to analysts credibility with users

Weaknesses Time Consuming May bias future

work design towards way things are currently done

Reviewing internal documents Strengths

Good way to learn history and politics

Explains current context

May help understand why and way of current procedures & applications

Weaknesses May bias future

work design Not useful for

obtaining current attitudes or motives

Modern Methods for Determining System Requirements

Prototyping Joint Application Design (JAD) - Intensive

meetings between users, managers, sponsor, & systems analysts to discuss & review system requirements

Group Support Systems (GSS) to share ideas & voice opinions

BPR – Business process reengineering CASE tools to analyze existing systems