CHAPTER 10

How to describe an information system?

What Is A System?

What Is A System?

A system is an organized set of related components established to accomplish a certain task

Examples

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Photo Source: http://www.wpclipart.com/

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Photo Source: http://www.solarviews.com/

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Photo Source: http://pt.wikipedia.org/wiki/Ficheiro:Traffic_Light_German_Complex_With_Bicycles.JPG

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Photo Source: http://www.flickr.com/photos/stuckincustoms/298010636/sizes/m/in/photostream/

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Photo Source: http://www.apple.com/

What do they have in common?

Identifying the IPOS helps us understand how a system works

What is IPOS?

IPOS

INPUT - What goes in

PROCESS - What happens

inside?

OUTPUT - What comes out?

IPO

S

Computerized Payroll System

INPUT Smart card

PROCESS Process in the computer

OUTPUT Printout

How can we visually describe a system?

Ways of describing a system

1. Structure diagram Top down approach

2. Data flow diagrams

3. System flowcharts

Top Down Diagrams

An overall task is broken down into smaller more manageable task and the process goes on and on as needed.

What are the steps involved?

1. Identify the main tasks to be done and then break them down into smaller tasks

2. Read from top to bottom – each big task is broken down into smaller tasks.

3. Read it left to right tells you the order in which they happen

Main Tasks

Smaller Tasks

Computerized Payroll System

INPUT Smart card

PROCESS Process in the computer

OUTPUT Printout

Enter Data Edit Data Print Report

AutomaticData

captureEdit Delete Update

ChoosePeriodRange

Summary- Individual- Group

- Statistics

Printrecord

Compute employee’s salary

Example: Employee’s Salary

Collect patient data

Enter patient data

Print patient data

Give patient Data Capture

Form

Patient completes

Data Capture Form

LoadPatient

file

CreateNew

record

EnterNew

record

CheckPrinter

Forpaper

Printpreview

Printrecord

Create new patient record

Example: Patient Record

Data Flow Diagrams

A graphical representation of the "flow" of data through an information system, modelling its process aspects.

A DFD shows what kinds of data will be input to and output from the system, where the data will come from and go to, and where the data will be stored. (Source: Wikipedia)

Symbols

Rectangle (box)

The source of data - shows where the data has come fromExamples: order form,

application form

Part of the system which uses or consumes the data, called a sinkExamples: customer, student

Sausage or bubble

Used to denote a process performed on the data

A process is something which is done to the dataExamples: calculation, sorting

data, combining data etc.

Open Rectangle

It represents a data store

Shows where the data is stored – this include a manual store of a hard copy

Arrows

It shows how the other symbols are connected

Doctor’s appointmentCustomer data file

Produce list of patients overdue

for an appointment

Merge fields into Appointment

Reminder letter

Standard lettersFile (template)

Copy kept in filing cabinet

Payroll System

Employee data file

Produce SUMMARY of login and logout

for the month

Calculate salary/wage based on the

summary

Employee/Accounting fileIs updatedAnd stored

System Flowcharts

A flowchart is a type of diagram that represents an algorithm or process, showing the steps as boxes of various kinds, and their order by connecting these with arrows. This diagrammatic representation can give a step-by-step solution to a given problem. (Source: Wikipedia)

Payroll System – time in

START

Record found?

Displayerror message

Recordupdated

END

Y N

Swipe card

New PatientSTART

CompletedBy

patient

Error?

Input byreceptionist

Validation

Valid? Displayerror message

Visual check

on form

A

Patientfile

Mail merge

Data capture form

Welcomeletter to

new patientNew patient

standard welcome

letter

END

Y

N

A

N

Y

Now it’s your turn…

Make a flowchart of the following activities:

Prepare a cup of hot coffee Watch your favorite TV show Call a friend Starting the computer

Development Timeline

A Gantt chart is a type of bar chart that illustrates a project schedule. Gantt charts illustrate the start and finish dates of the terminal elements and summary elements of a project.

END