Chapter – 8Systems Engineering: Analysis and Design

Book:- Waman S Jawadekar

Management Information System

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System Concepts• The word ‘System’ is used in day to day life. Eg. Education system, business

system etc.

• Definition:- System is defined as a set of elements arranged in an orderly manner to accomplish an objective.

• Example of System

Systems Elements Objective

Computer Input, process and output devices. OS, compilers etc.

Process the data and provide the information

Accounting Financial transactions, A/c principles and rules etc

Process the transactions and produce monthly books of accounts and information

Business Organization

People, plant & machinery, product & services, communication etc.

Produce goods and services to achieve the turnover and profit

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Contd..• System is arranged with some logic governed by rules,

regulations, principles and policies.

• Eg. If a computer system is designed for commercial data processing, then the elements will be the input device, CPU, disk, memory, app. Programme, printer etc.

• If it is designed for animation then graphic workstation, graphic processor and plotters etc. are required.

• Hence, a clear statement of objectives brings a precision and an order into the selection of elements and their arrangements in the system.

• System has three basic parts, which are organized in an orderly manner.

Input OutputProcess

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Contd..• A system may have single input and multiple outputs or may

have several inputs and outputs. • Eg. A business organization has several inputs and multiple

objectives such as sales, profit etc.• The choice of inputs and processing methodology is governed by

the objectives set for the system. Any misalignment in this arrangement would lead to a wasteful collection of input and its processing will fail to achieve the desired objective.

• All the systems operate in an environment. The environment may influence the system in its design and performance. When a system is designed to achieve certain objectives, it automatically sets the boundaries for itself.

• If additional objective is to be introduced in the system, it may be possible as the new objective may fall outside the boundaries or scope of the system.

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Generalized Model of a System

Input OutputProcess

Environment

The environment influences the choice of inputs, the method of processing, and the nature and contents of the outputs.

Since the systems are designed for specific objectives/outputs, the designer provides a filter around the system to control the influence on the system.

Most of the failures of the systems lie in the area of selection of the inputs and the processes, and not providing the appropriate filtering systems.

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Systems Control• The system control becomes the integral part of the system

design and ensures the achievement of the objectives.• The control means a measurement of the output in some terms. • The device that measures the output is called a sensor.• The standards or norms of the output as an index of the system

performance is set.• The sensor measures the output and compares it with the

standard. If the measured output compares well with the standard, the system provides a feedback to continue the operations else to stop the operations.

• The process of comparison of a measured output with the standard is done by a unit called as comparison unit

• The mechanism which provides a signal to the system, about the quality of performance, favourable or adverse is called a feedback mechanism

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Contd..• Sometimes, the system may not have an appropriate mechanism to act

on the signal which it receives. It is therefore, necessary to provide an inbuilt mechanism which will decide, based on the feedback to stop, regulate or continue the system operations.

• Such a mechanism is called a corrective unit and it is responsible for ensuring the system performance.

• The process of measuring the output, comparing with the standard, sending the signal to the corrective unit and the corrective unit acting upon it is called a control.

• The role of a control is to regulate the system operations and performance, and keep it in an equilibrium condition. The control, therefore, is the heart and brain of the system.

• The control can be internal or external to the system. (automatic)

• When the environmental factors or the inputs change, the system process is under a stress.

• The concept of control is based on the condition of a feedback.

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Control System model

Input OutputProcess

Corrective Unit

Comparison Unit

Sensor

Standard

Channels of

feedback

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Control System model for Data processing

Input data Computed ResultUse of prog. For processing

Corrective Unit

Compare result

Summary of result

Target Results

feedback

Positive or Negative

Change prog. If necessary

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MIS model of Quality Assurance

Raw materialwt, size, color, quantityManufacturing

Process

Corrective Unit

Weight control chart

weight

Upper and lower limits

Feedback through plotting of weights

Action to correct the process

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MIS and Support to BusinessSystem

ComponentsBusiness System MIS

Inputs Raw materials, plant and machinery, manufacturing, selling arrangement, accounting

Data from transactions of purchase, production and sales, receipts and payments

Process Purchasing, manufacturing, selling, accounting

Transaction processing and data processing

Outputs Quantity of production, sales, stock, income and profit

Computation of production in numbers, sales in values, stocks in weight etc.

Sensor Profit Income less assigned cost

Comparison unit

Expectation of profit VS actual profit Compare income vs budgeted income profit vs budgeted profit

Standard Profit, target. Budgeted profit of various prod.

Feedback Balance sheet and analysis Exception reports

Corrective unit

Managing director. Business decisions

Marketing manager. Pricing, advertising and promoting decisions.

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Types of System• A system is defined and determined by its boundaries and objectives.

• It is quite likely that a system is an arrangement of smaller systems in a logical order. When many smaller systems together make a larger system, the smaller systems are called the subsystems of the larger system.

• A large system can be split or decomposed into smaller subsystems up to a certain level.

• The decomposition of a system into subsystems can be in a serial form or it could be in a matrix form.

• In a serial system processing, the entire output of a subsystem is the input of the next subsystem and so on.

Subsystem

1

Manufacturing

Subsystem

3

Marketing

Subsystem

2

Quality control

Subsystems in Serial order

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Contd..In the matrix arrangement the different outputs go to different subsystems. A

subsystem receives more than one input from other subsystem.

Subsystem

1

Manufacturing

Subsystem

3

Marketing

Subsystem

2

Quality control

Subsystem

4

Accounting

Subsystems Operating in Matrix Order

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Contd..• The inputs are transformed into the output by the process. But, if the process

of input transformation is not visible and understandable then we say that the system is black box and the process is not transparent.

• A large system is always complex and difficult to understand. So for viewing it in a different way, the system is split into the smaller subsystems.

Inputs OutputsProcess

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Types of Systems (Contd..)• Most of the systems can also be viewed in a hierarchical structure. • Breaking the system in a hierarchical manner provides a way to

structured systems analysis. It gives a clear understanding of the contribution of each subsystem in terms of data flow and decisions, and its interface to the other subsystems.

• The systems can be classified in different categories based on the predictability of its output and the degree of information exchange with the environment.

• A system is called deterministic when the inputs, the process and the outputs are known with certainty.

• A system is called probabilistic when the output can only be predicted in probabilistic one.

• Eg. The accounting system is deterministic while the demand forecasting system is a probabilistic one.

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Hierarchical Structure

Bill Passing System

Computing Bill Amount Payable

Collating Bill to Goods Receipt

Collating Bill to purchase order

Auditing for Payment

Bill Scrutiny VS Goods received

Bill BookingBill Scrutiny

Main System Level - 1

Main System Level - 2

Main System Level - 3

Collate = Collect / Gather

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Contd..• Closed System:- If a system is functioning in isolation from the

environment, then the system does not have any exchange with the environment nor it is influenced by the environmental changes. Such a system is called a closed system.

• Open System:- If the system has exchange with the environment and is influenced by the environment then it is called an open system.

• All kinds of accounting systems viz. cash, stocks, attendance are closed systems. Most of the systems based on rules and principles are closed systems.

• The systems which are required to respond to changes in the environment, such as marketing, communication and forecasting are open systems.

• The information system is a combination of a person, the hardware and the software. The hardware-software system is a closed deterministic system but in combination with the user it is an open and a probabilistic system.

• Generally the deterministic systems are closed, and the probabilistic systems are open.

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Handling System complexity• IS are relatively complex as compared to physical systems, and therefore

they should be handled properly enabling the system designer to understand, design, develop and implement.

• To handle the complexity, the system can be viewed as an assembly of subsystems each with clear definition of the boundaries, interfaces and their connectivity. The subsystems then are put in the hierarchical order to provide a structural view showing the development path to the designer. The process is called factorisation of the system into subsystems.

• Another method of handling the complexity is to resort to simplification by clustering the subsystems together.

• The method of simplification is as follows:– Step 1: Identify the subsystems which have to be together for the

functional ‘cohesion’– Step 2: Form a cluster of these subsystems and identify

interconnections in this cluster.– Step 3: Form clusters of the remaining subsystems– Step 4: Connect the clusters with an interface.

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Eg. With Materials Management System

• Materials Management system can be subdivided into the following subsystems for the purpose of handling the complexity as shown in step 1.– (A) Procurement System

– (B) Purchase order follow up system.

– (C) Receipts accounting system

– (D) Material requirement planning system

– (E) Material issue requisition system

– (F) Bill passing and payment system

– (G) Inventory control system

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Contd.. Step - 2

A

B E

C D F

G

(A) Procurement System(B) Purchase order follow up system.(C) Receipts accounting system(D) Material requirement planning system(E) Material issue requisition system(F) Bill passing and payment system(G) Inventory control system

Factorisation Process

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Step - 3

A

B

E

C D

F

G

Cluster 1

Purchase Function

Cluster 2

Stock Accounting Function

Cluster 3

Materials planning & Control function

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Step 4:- Decoupling of subsystems

A

B

E

C D

F

GInterface Interface

Purchase information

stock information

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System Efficiency and Effectiveness• The performance of the system can be measured by two factors

viz. the efficiency and the effectiveness.• The efficiency indicates the manner in which the inputs are used

by the system. If the input-output ratio is adverse, we say that the system is inefficient though it produces the desired output.

• The effectiveness is the measure for deciding whether the system provides the desired output or not. Being effective means producing the right output in terms of quantity and quality.

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Post Implementation problems in a System• When systems are allowed to run for sometime, they tend to become

disorganized, resulting into system inefficiency• The process of decay and its cause is called ‘Entropy’ (a numerical

measure of the uncertainty of an outcome) . The designer introduce negative entropy i.e to provide a course of action, whereby the decay is arrested and the system is brought back to the state of equilibrium, producing the desired objectives.

• The process of providing a negative entropy is called system maintenance.

• As a preventive measure, a negative entropy is provided as a part of the system routine. – (a) A periodical review of the system– (b) User meetings to assess the current utility of the system and the

level of satisfaction.– (c) Subjecting the system to an audit check through the test data– (d) Running the system under audit trail– (e) Bringing out system modifications.

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System Maintenance Procedure

System Indications of entropy

Negative entropy

Human body Loss of weight, headache

Medical check-up and prescribed diet and medicines

Computer System halts, read and write errors

Preventive maintenance and replacement of sensitive components

Data processing Errors and omissions in the data on increase

Review and introduction of the streamlined procedures

Information processing

Decline in the utility and satisfaction, changed information needs

Resetting the goals of information system. Add revised information needs and modify the information system

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Contd..• Key to handle post implementation problems in the systems are:

– (a) The core system design must be comprehensive and flexible to undergo a quick change.

– (b) The associated peripheral systems should be built with a flexible design.

• The most successful way or handling these problems is to have a business analyst in the organization and perceive the business needs of the information and user object oriented technology for efficient system design

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Classes of Systems• MIS systems are classified in five classes as under:

– Data Processing system (DPS)

– Transaction processing system (TPS)

– Application processing system (APS)

– Business function processing system (BPS)

– Integrated information processing system (IPS)

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Data Processing System (DPS)• DPS is designed to capture, collect or enter the data to process in a

certain specified manner to achieve the following:

– Data is complete correct and valid from all aspects

– Such data then is processed and organized in some form for further processing

– DPS may have an algorithm using one or more data inputs and may produce one or more outputs.

– Eg. Is employee’s daily attendance processing system designed to provide monthly attendance for payroll application.

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Model of DPS

System of Capture, collect, Enter

System of Scrutiny, checking

System of Result processing

Query Processing

Reports

Master Files

ResultsRecordFile(s)Display

Data Input

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Transaction processing system (TPS)• TPS is designed to handle a transaction between parties. The

parties could be two or more and have a designated role in TPS. • TPS uses data files, master files, transaction records and processes

the data in a manner specified. • TPS output is a transaction in itself and updating the various other

records based on the result processed as a part of the transaction execution.

• Eg. In a payroll system, the payment of monthly salary to an employee is a transaction. It considers payment rules, employee payable days and salary payment terms of the employee.

• This transaction uses employee master file, payable days, and salary computing algorithm to compute the payable salary. In this transaction parties are organization and employee.

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Model of TPS

Master Files

TransactionProcess

algorithm

Transaction Data Files

TPS for accuracy, completeness, consistency, validity and decision for acceptance or rejection

ProceedTransaction

File(s)

Report orDocument

OutputQuery Processing

Display

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Application processing system (APS)• APS is built over DPSs and TPSs. • APS uses files created by DPS and TPS and applies

application processing rules to execute the application.• APS may have an output as a document, a report or a set

of results required for processing further in business function system.

• Eg. Billing the customer is an application. This application uses output files of following TPSs– Customer order ack– Product delivery to customer– Delivery ack and acceptance by the customer.

• Billing APS produces bill on the customer and produces number of results to update post billing effect elsewhere

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Model of APS

Master Files

Application Processing

rules

Processed Data Files

APS for verification, checking, selecting rules, computing formulae and formatting

ApplicationOutput file &

records

Report orDocument

ReportQuery Processing

Display

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Business function processing system (BPS)• BPS deals with business functions. BPS aids in business function

processing and helps management in decision making required within the scope of a business function.

• It brings out more MIS reports for business function management, such as Sales, Production, Materials etc.

• For eg. sales function is built on applications like order processing, order manufacturing, delivery, billing and accounting.

• Business system uses relevant APS and TPS outputs for processing the system results.

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Model of BPS

TransactionOutput file

SystemProcessing

rules

Application Process system

Output filesSystem processing after checking file consistency, validity

System ResultFile(s)

Future MISReports

Query Processing

QueryDisplay

Summary ofResults fileFor DSS

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Integrated Information processing system (IPS)• IPS sits on the top of the rest of the systems ie DPS, TPS, APS, BPS.• IPS draws its input from these systems and applies information

processing rules to bring out an output.• IPS meets a requirement of top management in the area of

planning, budgeting and strategic control.• Eg. of IPS are project planning, capital budgeting, manufacturing

planning, preparing year end balance sheet schedules and reports.• IPS is an integrated information processing system for producing

information supporting top management’s decision making.

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Model of IPS

ResultsDB

TPSOutput

files

IP rules, Models,

Algorithms

Use of information process tools

Reports

Spread Sheet Applications (SSA)

APSOutput

files

FunctionDB &

Metadata

KnowledgeDB

Executive Information System (EIS)

Data Warehousing System (DWH)

Data Mining System (DMS)

Knowledge Process System (KPS)