ITEC 3010 “Systems Analysis and Design, I”
Introduction to Systems Analysis.
[Prof. Peter Khaiter]
General Systems Theory
Feedback and Control
Concepts of Separation
Types of Information Systems
Systems Analyst: problem solver
IT and Strategic Planning
RMO Case Study: Intro 2
I. General Systems Theory
1. System’s Concept
Def. A System is a set of components that interact
with one another and serve for a common
purpose or goal.
Systems may be: (1) abstract or (2) physical
• An abstract system is conceptual, a product of a human
mind. That is, it cannot be seen or pointed to as an
existing entity. Social, theological, cultural systems are
abstract systems. None of them can be photographed,
drawn or otherwise physically pictured. However, they do
exist and can be discussed, studied and analyzed.
• A physical system, in contrast, has a material nature. It is
based on material basis rather than on ideas or theoretical
Nine System’s Characteristics
1. Components 2. Interrelationships
3. Boundary 4. Purpose
5. Environment 6. Input
7. Output 8. Interface
System’s Concept (cont’d)
FIGURE 1-1 Characteristics of a system
2. System’s Characteristics (1 of 3)
• A component is either an irreducible part or an
aggregate of parts, also called a subsystem. The
simple concept of a component is very powerful. For
example, in case of an automobile we can repair or
upgrade the system by changing individual
components without having to make changes the
• The components are interrelated; that is, the
function of one is somehow tied to the function of the
others. For example, in the Store system the work of
one component, such as producing a daily report of
customer orders, may not progress successfully until
the work of another component is finished, such as
sorting customer orders by date of receipt. 6
System’s Characteristics (2 of 3)
• A system has a boundary, within which all of its
components are contained and which establishes the
limits of a system, separating it from other systems.
• All of the components work together to achieve
some overall purpose: the system’s reason for
• A system operates within an environment –
everything outside the system’s boundary. The
environment surrounds the system, both affecting it
and being affected by it.
E.g.: the environment of a university includes prospective students,
foundations, funding agencies and the new media. Usually the system
interacts with its environment. A university interacts with prospective
students by having open houses and recruiting from local high schools.
System’s Characteristics (3 of 3)
• The point at which the system meets its environment are
• A system must face constraints in its functioning because
there are limits to what it can do and how it can achieve its
purpose within its environment. Some of these constraints are
imposed inside the system (e.g., a limited number of staff
Others are imposed by the environment (e.g., due to
• A system interact with the environment by means of inputs
and outputs. Input is anything entering the system from the
environment; output is anything leaving the system crossing
the boundary to the environment . Information, energy, and
material can be both input and output in relation to the
E.g.: People take in food, oxygen, and water from the environment as input. An electrical
utility takes on input from the environment in the form of raw materials (coal, oil,
water power, etc), requests for electricity from customers. It provides for output to the
environment in the form of electricity. 8
3. Feedback and Control in a
System (1 of 4)
Very often output data are being returned to the input of the
system, as shown in Fig. 1-2, and used to regulate the
FIGURE 1-2 Regulation of activity 9
Feedback and Control in a System
(2 of 4)
Such a process is called feedback. It helps to
adjust the system to changes so that the system
operates in a balanced state, or equilibrium.
E.g.: Large hotels and motels, for instance, ask
guests to fill out cards evaluating the services. This
feature of a system is used in control.
Def. Control is the process that measures current
performance and guides it toward a predetermined
Two types of feedback are related to system
control: (1) negative and (2) positive
Feedback and Control in a System
(3 of 4)
Negative feedback is corrective feedback that helps maintain the
system within a critical operating range and reduces fluctuations
around the norm or standard.
Negative feedback is transmitted in feedback control loops.
As shown in Figure 1-3, a sensor detects the effect of output on the
external environment; this information is returned to the system as
an input, and necessary adjustments are made according to
In contrast to negative feedback, which is corrective, positive
feedback reinforces the operation of a system by causing it to
continue its performance and activities without changes.
Feedback and Control in a System
(4 of 4)
FIGURE 1-3 Feedback control loops
4. Methods of system’s study (1 of 3)
There are several important system’s concepts that help to study a
system and understand its functioning:
Decomposition is the process of breaking down a system into
its smaller components. These components may themselves be
systems (subsystems) and can be broken down into their
components as well. How does decomposition aid
understanding of a system? It results in smaller and less
complex pieces that are easier to understand than larger,
Methods of system’s study (2 of 3)
FIGURE 1-4 Decomposing a CD system
Methods of system’s study (3 of 3)
Modularity is a direct result of decomposition. It refers to dividing a
system into chunks or modules of a relatively uniform size. Modules
can represent a system simply, making it easier to redesign and
E.g.: a portable CD player, as a system, accepts CDs and settings of
volume and tone as inputs and produces music as output. It includes
the separate systems as its subsystems: 1) read the digital signals
from CDs; 2) amplify the signals; 3) turn the signals into sound
waves; and 4) control the volume and tone of the sound (see Figure
Coupling means that subsystems are dependent on each other. But
they should be as independent as possible. If one subsystem fails and
other subsystems are highly dependent on it, the others will either fail
themselves or have problems functioning.
Cohesion is the extend to which a subsystem performs a single
function. In the CD player example, signal reading is a single
5. “Systems” Thinking
Being able to identify something as a system
Involves being able to identify subsystems
Identifying system characteristics and functions
Identifying where the boundaries are (or should be)
Identifying inputs and outputs to systems
Identifying relationships among subsystems
II. Information Systems
1. Information System, Subsystem
Informational nature of Control and Management
Possible inputs and outputs: information, energy,
use only information
Information is the central core of feedback loops
while regulating the system activities.
Special systems for processing and handling
provide management with information for making decisions
Def. An Information System (IS) is a
collection of interrelated components that
collect, process, store, and provide as
output the information needed to complete
a business task.
E.g.: A payroll system collects information
on employees and their work, processes
and stores that information, and than
produces paychecks and payroll reports for
the organization. Then information is
provided to manufacturing so the
department can schedule production.
Hierarchy of Information Systems (1 of 3)
Hierarchy: System, Subsystem, Supersystem
E.g.: customer support system: order entry subsystem, order
fulfillment subsystem, shipping and back order subsystem, product
catalog maintenance, etc.
Supersystem – a larger system that includes the system. The system is
a subsystem of the larger supersystem
E.g.: production system includes other systems, such as inventory
management and manufacturing and customer support system (Figure
Different view of an information system: a list of its components:
hardware, software, inputs, outputs, data, people, and procedures
Hierarchy of Information Systems (2 of 3)
FIGURE 1-5 Information systems and subsystems 20
Hierarchy of Information Systems (3 of 3)
FIGURE 1-6 Information system and component parts 21
System Boundary vs. Automation
System boundary: separates system from other systems and
from its environment
Automation boundary - separates the automated part of the IS
(where work is done by computers) from the manual part (where
work is done by the people).
FIGURE 1-7 The
system boundary vs.
2. Concepts of Separation (1 of 8)
Separating Data from Processes That Handle Data
Every IS as a three-component system (Fig. 1-8):
• data flows
• processing logic
Data are raw facts that describe people, objects and events in
organization (e.g. name, age, customer’s account number). Data is
used in an IS to produce information
Information is data organized in a form that human can interpret
Data flows are group of data that move and flow through a system.
They include a description of the sources and destinations for each
Processing logic describes the steps that transform the data and events
that trigger these steps
Concepts of Separation (2 of 8)
Concepts of Separation (3 of 8)
Two approaches to IS design:
Concepts of Separation (4 of 8)
The process-oriented approach is based on what the system is
supposed to do.
The focus is on output and processing logic.
Although the data are important, but are secondary to the
Each application contains its own files and data storage
E.g.: Figure 1-9(A): “personnel data” appears in two separate
systems – payroll system and the project management system.
If a single element changes, it has to be changed in each of the
This approach involves creating graphical presentations (data
flow diagram and charts).
Concepts of Separation (5 of 8)
The data-oriented approach: an ideal
organization of data, independent of where and
how data are used within the system
Avoids data duplication and redundancy (see
This approach uses data model that describes
the kinds of data needed in the system and the
business relationships among the data (i.e.
Table 1-10 summarizes the differences between
the two approaches.
Concepts of Separation (6 of 8)
FIGURE 1-9 The Relationship Between Data and Applications:
(A) Process-Oriented Approach
(B) Data-Oriented Approach
Concepts of Separation (7 of 8)
Table 1-10 Key Differences Between The Process-Oriented and Data-
Concepts of Separation (8 of 8)
Separating Databases from Applications
When the data-oriented approach is applied, databases are
designed around subjects, such as customers, suppliers and parts.
It allows to use and to revise databases for many different
independent applications, what creates the principle of application
independence (i.e. separation of data and definition of data from
3. Types of Information Systems (1 of 5)
Different types of activity require different types of information systems to
support all the needs (e.g., transaction processing systems, management
information systems, executive information systems, decision support
systems, expert systems, communication support systems, and office
support systems) - Figure 1-11
Transaction processing systems (TPS) capture and record information
about the transactions that affect the organization.
A transaction occurs each time a sale is made, supplies are ordered, an
interest payment is made.
Usually these transactions create credit or debit entries in accounting
This kind of ISs were among the first to be automated by computers.
Modern TPS use state-of-the-art technology, e.g., on-line TPS.
Types of Information Systems (2 of 5)
FIGURE 1-11 Types of
Types of Information Systems (3 of 5)
Management information systems (MIS) are systems that
take information captured by TPS and produce reports that
management needs for planning and controlling the business.
MIS are possible because the information has been captured by
the TPS and placed in organizational databases.
Executive information systems (EIS) provide information for
executives to use in strategic planning.
Some of the information comes from the organizational
databases, but much of the information comes from external
sources: news about competitors, stock market reports,
economic forecasts, and so on.
Types of Information Systems (4 of 5)
Decision support systems (DSS) allow a user to explore the impact of
available options or decisions.
Whereas an MIS produce reports, DSS provide an interactive environment
in which decision makers can quickly manipulate data and models of
A DSS has three parts: (1) the first part is composed of a database (which
may be extracted from TPS or MIS); (2) the second part consists of
mathematical or graphical models of business processes; (3) the third part is
made up of a user interface (or dialogue module) that provides a way for
the decision makers to communicate with the DSS.
An EIS is a DSS that allows senior management to explore data starting at
a high level of aggregation and selectively drill down into specific areas
where more detailed information and analysis are required.
Types of Information Systems (5 of 5)
Expert systems (ES) replicate the decision-making process rather than
If-then-else rules or other knowledge representation forms describe the way a
real expert would approach situations in a specific domain of problems.
Typically, users communicate with an ES through an interactive dialogue.
The ES asks questions (which an expert would ask) and the end user supplies
the answers. Those answers are then used to determine which rules apply, and
the ES provides a recommendation based on the rules.
Communication support systems (CSS) allow employees to communicate
with each other and with customers and suppliers. Communication support
now includes e-mail, fax, Internet access, and video conferencing.
Office support systems (OSS) help employees create and share documents,
including reports, proposals, and memos. OSS also help to maintain
information about work schedule and meetings.
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