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Presentation on theme: "MODELLING AND FEASIBILITY"— Presentation transcript:


2 System modelling System modelling helps the analyst to understand the functionality of the system and models are used to communicate with customers

3 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.

4 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.

5 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.

6 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.

7 Process modeling – a technique used to organize and document a system’s processes.
Flow of data through processes Logic Policies Procedures

8 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.

9 Simple Data Flow Diagram

10 Process Concepts Process – work performed by a system in response to incoming data flows or conditions. A synonym is transform.

11 Process Concepts

12 Decomposition Diagrams
Decomposition diagram – a tool used to depict the decomposition of a system. Also called hierarchy chart.

13 Decomposition Diagram

14 Common Process Errors on DFDs

15 Data Flows to and from Data Stores

16 Illegal Data Flows

17 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.

18 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.

19 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.


21 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.

22 Problems with Natural English ….
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.

23 Problems with Natural English.…
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.

24 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.

25 Decision Table

26 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.

27 Decision Tree

28 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.

29 Feasibility Analysis/Assessment
This presentation will probably involve audience discussion, which will create action items. Use PowerPoint to keep track of these action items during your presentation In Slide Show, click on the right mouse button Select “Meeting Minder” Select the “Action Items” tab Type in action items as they come up Click OK to dismiss this box This will automatically create an Action Item slide at the end of your presentation with your points entered. Feasibility Analysis/Assessment

30 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.

31 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.

32 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

33 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.

34 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.

35 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.

36 Tests of Feasibility Operational Feasibility Technical Feasibility
Schedule Feasibility Economic Feasibility

37 Tests of Feasibility…. 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?

38 Tests of Feasibility….. Schedule Feasibility
How reasonable is the project timetable? Economic Feasibility How cost-effective is the project or solution? Cost-benefit analysis

39 Operational Feasibility
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?

40 Operational Feasibility….
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?

41 Operational Feasibility….
Included here are: Manpower problems Management resistance Organizational conflicts Legal aspects Government regulations

42 Operational Feasibility….
It evaluates whether the system can work or will work. A workable solution might fail because of end-user or management resistance.

43 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.

44 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.

45 Technical Feasibility
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?

46 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.

47 Schedule Feasibility Technology could be available but not expertise, learning new technology can impact on the schedule. Are projects deadlines reasonable Are deadlines mandatory or desirable How far can the deadlines be extended What are the cost associated with such extensions in deadlines. Missed schedules are bad, but inadequate systems are worse.

48 Economic Feasibility 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

49 Economic Feasibility…
Cost-benefit analyses How much will the system cost? Development costs Operation costs Maintenance and support costs

50 Benefit Analysis 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.

51 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

52 Economic Feasibility Payback analysis
How long will it take to recoup the costs of this project? Return on investment (ROI) analysis Estimated lifetime benefits - estimated lifetime cost Estimated lifetime cost Net present value analysis (translates the future income to the present value)

53 Compare candidate systems on basis of several characteristics
Feasibility Analysis Compare candidate systems on basis of several characteristics Better analysts always consider multiple solutions

54 Legal and Contractual Feasibility
The process of assessing potential legal and contractual ramifications due to the construction of a system e.g. Copyright Labor laws Foreign trade legislation Financial reporting standards Ownership of software License agreement for software and hardware

55 Market and Real Estate Feasibility
Market 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.

56 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.

57 Cultural Feasibility In 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.

58 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 system



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