MODELLING

AND

FEASIBILITY 1

System modelling

System modelling helps the analyst to

understand the functionality of the

system and models are used to

communicate with customers

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What is a model?

Model – a pictorial representation of

reality.

– Just as a picture is worth a thousand

words, most models are pictorial

representations of reality.

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Models: Logical and Physical

Logical model – a non technical pictorial representation that depicts what a system is or does. Synonyms with essential model, conceptual model, and business model. Physical model – a technical pictorial representation that depicts what a system is or does and how the system is implemented. Synonyms are implementation model and technical model.

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Why Logical System Models

Logical models remove biases that are

the result of the way the system is

currently implemented, or the way that

any one person thinks the system

might be implemented.

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Why Logical System Models….

Logical models reduce the risk of missing

business requirements because we are too

preoccupied with technical results.

Logical models allow us to communicate

with end-users in non technical or less

technical languages.

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Process modeling – a technique used

to organize and document a system’s

processes.

– Flow of data through processes

– Logic

– Policies

– Procedures

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Data flow diagram (DFD) – a process model

used to depict the flow of data through a

system and the work or processing performed

by the system. Synonyms are bubble chart,

transformation graph, and process model.

DFDs have become a popular tool for

business process redesign.

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Simple Data Flow Diagram

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Process Concepts

Process – work performed by a

system in response to incoming data

flows or conditions. A synonym is

transform.

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Process Concepts

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Decomposition Diagrams

Decomposition diagram – a tool

used to depict the decomposition

of a system. Also called hierarchy

chart.

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Decomposition Diagram

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Common Process Errors on DFDs

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Data Flows to and from Data Stores

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Illegal Data Flows

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Process Logic

Decomposition diagrams and data

flow diagrams are effective tools for

identifying processes, but are not

good at showing the logic inside those

processes.

– Eventually need to specify detailed

instructions.

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Process Logic…..

– Should effectively communicate

with both users and programmers.

– Flowcharts and pseudo code are

difficult for users to understand.

– Structured English has advantages

over natural English with some of

the rigor of programming logic.18

Modeling Logic With Structured English

Stuctured English is a modified form of

English used to specify the logic of

information system processes. Although

there is no single standard, structured

English typically relies on action verbs

and noun phrases and contains no

adjectives or adverbs.19

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Problems with Natural English

Many of us do not write well, and we

also tend not to question our writing

abilities.

Many of us are too educated to

communicate with an audience that

may not have had the same

educational opportunities.

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Some of us write everything like it was

a program. If business procedures

required such precision, we’d write

everything in a programming language.

Too often, we allow the jargon and

acronyms of computing to dominate our

language.

Problems with Natural English ….

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English statements frequently have an excessive or confusing scope.

We overuse compound sentences Too many words have multiple definitions. Too many statements use imprecise adjectives. Conditional instructions can be imprecise. Compound conditions tend to show up in

natural English.

Problems with Natural English.…

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Modeling Logic With Decision Tables

Structured English can become more difficult to understand and verify as logic becomes more complicated. A diagram becomes more clearer. A decision table is a diagram of process logic where logic is reasonably complicated. All the possible choices and the conditions are represented in tabular form. 24

Decision Table

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Modeling Logic With Decision Trees

A decision tree is a graphical technique that depicts a decision or choice situation as a connected series of nodes and branches. The decision tree used here is not a management science decision tree where one chooses the best among alternatives. This one is without probabilities and is used to diagram the same sort of situations for which decision tables were used. 26

Decision Tree

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Both decision tables and decision trees are used as communication tools designed to make it easier for analysts to communicate with users. How to decide whether to use Flowcharts, Structured English, Decision Tables or Decision Trees when modeling process logic depends on whichever method you prefer and understand best. But mostly it depends on task you are performing. 28

Feasibility

Analysis/Assessment

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The assessment is based on an outline

design of system requirements in terms

of Input, Processes, Output, Fields,

Programs, and Procedures. This can be

quantified in terms of volumes of data,

trends, frequency of updating, etc. in

order to estimate whether the new

system will perform adequately or not.

This means that feasibility is a study

based on outline. 30

Feasibility analysis is the process by which feasibility is measured. – Feasibility should be measured

throughout the life cycle. – The scope and complexity of an

apparently feasible project can change after the initial problems and opportunities are fully analyzed or after the system has been designed.

– Thus, a project that is feasible at one point in time may become infeasible at a later point in time.

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Feasibility Assessment Why feasibility assessment?

– Information systems are major investments

– IS projects are subject to the same cost justifications as any other capital investments

– Business value paradox (hard to explain)

– Avoid "black hole" projects 32

Feasibility Checkpoints During Analysis

– Systems Analysis -Survey Phase

• ``Do the problems (or opportunities) warrant the cost of a detailed study of the current system?''

– Systems Analysis -  Study/Definition Phase

• Better estimates of development costs and the benefits to be obtained from a new system. 33

Feasibility Checkpoints …

• Requirements often prove to be more extensive than originally stated.

• If feasibility is in question, scope, schedule, and costs must be rejustified.

– Systems Analysis - Selection Phase

• A major feasibility analysis evaluating options for the target systems design. 34

Feasibility Checkpoints …– Typical options that are evaluated include

• Do nothing! Leave the current system alone.

• Reengineer the (manual) business processes, not the computer-based processes.

• Enhance existing computer processes.

• Purchase a packaged application.

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• Operational Feasibility

• Technical Feasibility

• Schedule Feasibility

• Economic Feasibility

Tests of Feasibility

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• Operational Feasibility How well will the solution work in the organization?

• Technical Feasibility How practical is the technical solution?How available are technical resources and expertise?

Tests of Feasibility….

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• Schedule Feasibility How reasonable is the project timetable?

• Economic Feasibility How cost-effective is the project or solution?Cost-benefit analysis

Tests of Feasibility…..

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• Questions to Ask Is the problem worth solving? Will the solution to the problem

work? How do end users and

management feel about the solution?

What might end-users and management resist in the new system? Can it be overcome?

Operational Feasibility

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Has a usability analysis been

conducted? How will the working environment of

users change?

Operational feasibility defines the

urgency of the problem and the

acceptability of the solution. It should

answer the following question: If the

system is developed, will it be used?

Operational Feasibility….

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Operational Feasibility….

Included here are:

Manpower problems

Management resistance

Organizational conflicts

Legal aspects

Government regulations41

Operational Feasibility….

It evaluates whether the system

can work or will work. A

workable solution might fail

because of end-user or

management resistance.

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Using Pieces Frame Work

Performance- the system should provide

adequate throughput and response time

Information- the system should provide

end users with timely, pertinent, accurate

and useful information.

Economy- system should offer adequate

services at reduced cost.

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Using Pieces Frame Work...

Control-the system should have

adequate controls to ensure

confidentiality, integrity and availability

Efficiency- make optimum use of the

resources available.

Services- the system should be reliable,

flexible and expandable.

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• Questions to Ask Is the proposed solution

practical? Do we possess the necessary

technology? Do we possess the necessary

technical expertise? Is the technology mature enough

to be applied to the problem? If technology is not available, can

it be acquired?

Technical Feasibility

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Technical Feasibility….

Some people prefer state-of-art

technology, but most firms prefer to

use proven technology because of

large customer base for obtaining

advice concerning problems and

continuous improvement.

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Schedule FeasibilityTechnology could be available but not expertise, learning new technology can impact on the schedule.

Are projects deadlines reasonableAre deadlines mandatory or desirableHow far can the deadlines be extendedWhat are the cost associated with such

extensions in deadlines.

Missed schedules are bad, but inadequate systems are worse. 47

Many projects are economically

feasible, the question to ask here is:

Are the possible benefits of solving

the problem worthwhile?

Economic feasibility is a measure of

the cost-effectiveness of a project or

solution

Economic Feasibility

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Economic Feasibility…

Cost-benefit analyses

How much will the system cost?Development costsOperation costsMaintenance and support costs

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•Benefit analyses Tangible benefits can be easily

quantified. Measured in terms of monthly or

annual savings, or of profit to

organization Intangible benefits more difficult

to quantify.

Benefit Analysis

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Benefit Analysis

Tangible Benefits Fewer processing errors Increased throughput Decreased response time Elimination of job steps Increased sales Reduced credit losses Reduced expenses Opening of new markets Improvement of

Management and planning

Intangible Benefits Improved customer

goodwill Improved employee

morale Better service to

community Better decision-making Improved asset

utilization Improved resource

control

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Economic Feasibility

Payback analysis– How long will it take to recoup the costs of

this project?

Return on investment (ROI) analysisEstimated lifetime benefits - estimated

lifetime costEstimated lifetime cost

Net present value analysis (translates the future income to the present value)

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Feasibility Analysis

Compare candidate systems on basis of several characteristics

– Better analysts always consider multiple solutions

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Legal and Contractual FeasibilityThe process of assessing potential legal and

contractual ramifications due to the construction of a system e.g.

CopyrightLabor lawsForeign trade legislationFinancial reporting standardsOwnership of softwareLicense agreement for software and hardware

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Market and Real Estate FeasibilityMarket Feasibility Study typically involves testing geographic locations for a real estate development project, and usually involves parcels of real estate land. Developers often conduct market studies to determine the best location within a jurisdiction, and to test alternative land uses for a given parcels.

Market Feasibility takes into account the importance of the business in the selected area.

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Resource Feasibility

This involves questions such as how

much time is available to build the new

system, when it can be built, whether it

interferes with normal business

operations, type and amount of resources

required, dependencies, etc. Contingency

and mitigation plans should also be stated

here.56

Cultural FeasibilityIn this stage, the project's alternatives are evaluated for their impact on the local and general culture. For example, environmental factors need to be considered and these factors are to be well known. For example, religion, language, believes, signs and symbols, mannerism, timeliness.

Further an enterprise's own culture can clash with the results of the project. People could have been benefiting from inefficiencies.

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Political Feasibility

The process of evaluating how key

stakeholders within the organization view

the proposed system e.g.

New system may affect distribution of

power

Stake holders may take steps to block,

disrupt or change the intended focus of the

system58

THE END

THANK YOU

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