System analysis and design

Module 1:

Information system concepts:

A system is a combination of resources working together to convert inputs into outputs.

Inputs are known as data, which are recordable facts. The outputs of a system are interpreted
data, which are called information.

Thus, data are unprocessed information.

Business information system:

A business information system uses resources to convert input to output.

The resources are used to accomplish the goal or purpose of the business. The resources may be
workers, facilities, materials and equipment.

The transformation of inputs into outputs is affected by certain constraints which are foreign (or
external) to the system.

Some examples of the constraints are federal laws, social environment, total market, raw
material limitations etc.

Business information are made up of smaller components that are known as subsystems. Each
subsystem performs different functions.

For example, finance system contains subsystems such as billing subsystem, collection
subsystem and paying subsystem.

Business system characteristics:

The purpose of a business can be defined in terms of goals and objectives.

A goal is a very broadly stated purpose and objectives are concrete and specific
accomplishments necessary to achieve the goal.

For example, for the goal of educating students, the college must have an objective which is the
curriculum or syllabus to achieve the goal.

Goals are relatively long term and objectives are relatively short term.

Most business enterprises fall into two categories: production and service.
Production enterprises are manufacturing, farming, construction etc. and service enterprises are
transportation, communication, education etc.

Information system levels:

The information system levels classifies information based on the tasks and
responsibilities.

The information system levels are of 4 types:

1. Operational level
2. Lower management level
3. Middle management level
4. Top management level

Operational level:

At the operational level, routine operations or clerical operations which refers to the
daily performing tasks.

Computer systems are used to perform basic activities and transactions, such as
processing orders, shipping and financial transactions.

Lower management level:

Lower management performs supervisory functions.

They schedule the routine operations which are then performed at the operational
level.

Responsibility of lower management is checking the results of the operations and

taking necessary actions.

Middle management level:

Middle-level managers make tactical decisions. Which includes decisions related to

developing plans.

This level this responsible for allocating resources necessary to accomplish objectives
that support strategic goals of the business.

The authority is delegated to the supervisory level.

Top management level:

It makes strategic decisions that affect and shape the future survivability of an
organization.

The organization chart:

The organization chart is a flowchart that identifies the organizational elements of a business
and displays areas of responsibility and lines of authority.

It is the responsibility of the top management to define and update the organization chart.

The designing of the organization chart is important because it stimulates the management to
keep its organizational plan up to date.

(Extra point: Organization charts are essential to system analyst. The system analyst deals with
individuals who have specific position in the organization.)

Most business organization charts are structured as a series of superior-subordinate

relationships.

Superior

Authority Subordinate Subordinate Responsibility

Subordinate

Rectangles specify positions, lines and arrow heads indicate the downward flow of authority and
upward flow of responsibility.

Organization charts can be expanded to display linkages between successive levels.

In most of the organization there is a horizontal linkage and vertical linkage.

Horizontal linkages are used to pass information to different functional areas in the same level
of an organization. Vertical linkages are used for superior subordinate reporting.
Positions for which both a superior and subordinate reporting relationship are shown are called
link pins.

The organization function list:

An organization function list provides information about the major activities performed by an
organization.

A separate function list is prepared for each person on the organization chart.

To be able to identify an organization function list, it uses the tiles and numbers of the specific
organization chart.

The system development life cycle (SDLC):

(Extra point: System Development Life Cycle (SDLC) is a model which includes procedures for
developing or altering systems throughout their life cycles.)

Systems are created by a dynamic process which goes through a series of phases.

The four major phases of SDLC are:

1. The study phase
2. The design phase
3. The development phase
4. The operation phase

The concept of life cycle describes the relationship between these phases.

This concept includes not only forward motion but also the possibility of having to return back.

The returning back occurs as a result of failure in any of those phases.

All of these activities associated with each life-cycle phase must be performed, managed and
documented.
The study phase:
This is the phase in which a problem is identified and analysed, alternate solutions identified and
system recommendation made at a general design level.

The recommendation involves selecting the resources needed to complete detailed design and
the development of the system.

The design phase:

In this phase, the system recommended by the study phase is accomplished.

The design phase activities include the allocation of resources to equipment tasks, personnel
tasks and computer program tasks.

The development phase:

This is the phase in which the computer based system is constructed from specifications in the
design phase.

Equipment is acquired and installed during the development phase and also the required
computer programs are written.

All necessary procedures, manuals, software specifications and other documentation are
completed. The staff is trained to test the new system.

The operation phase:

In this phase, the new system is installed or the old system is changed to new system created
from the development phase.

The new system is operated and maintained. Its performance is reviewed and changes in it are
managed.

Management review of the life cycle activities:

Management review of the life cycle can happen at any phase.

These are formal scheduled reviews that must occur before a phase can be considered
complete.

Three types of decision can be made from the reviews:

1. Proceed to the next phase

2. Cancel the project
3. Redo the certain parts of a previous phase

Activities that are redone must be reviewed before the project can proceed to the next phase.

Management review often triggers the mechanism of cycling back to an earlier phase that was
considered complete.
Documentation or Baseline specifications:

Performance specifications:
Completed at the conclusion of the study phase, and describing in the language of the user to
exactly what that system is to do. It is general “design to” specification.

Design specification:
Completed at the conclusion of the design phase, and describing in the language of the
programmer how to develop the system. It is a detailed “built to” specification.

System specification: (asked in previous ques papers)

Completed at the conclusion of the development phase and containing all of the critical system
documentation. It is a basis for manuals and procedures, and it is a complete “as built”
specification.

Functions of system analysis:

1. To analyse business systems with problems and to design new or modified systems to solve
those problems.

2. To develop business systems to meet new information or operational needs.

3. To prepare and maintain manuals to communicate company policies and procedures.

4. To design the various business forms used to collect data and to distribute information.

5. To prepare and maintain business organization charts.

Module 2:

Identification codes (ID):

Identification code is a group of characters used to identify a record of data.

For example, to identify employees in a certain organization, the employees are assigned
employee numbers.

The system analyst often use these identification codes during the study phase and design
phase.

Identification code plan:

The identification code plan identifies the particular characteristics that need to be contained
with the code.
Only the information that makes possible efficient identification of coded items should be
included.

Code planning include certain characteristics, they should be:

1. Expandable
2. Precise
3. Concise: the code should be as brief as possible.
4. Convenient: the code must be easy to encode and decode.
5. Meaningful
6. Operable: the code should work with machine processing.

Common types of codes:

There are five types of codes:

1. Sequence code
2. Group classification code
3. Significant digit code
4. Alpha numeric code
5. Self-checking code

Sequence code:
A sequence code has no relation to the characteristics of an item.

1. Simple sequence code

2. Block sequence code

Simple sequence code:

The assignment of consecutive numbers, for example: 1, 2, 3 etc. to a list of items as they occur
is called a simple sequence.

A simple sequence code structure is given below:

Code Emp_name
1 John
2 Mary
3 Nancy

The advantage of simple sequence code is its ability to code a large number of items with the
least number of code digits.

Its principal disadvantage is the limited amount of information it can convey.

Block sequence code:

In a block sequence code, a series of consecutive numbers and/or letters is divided into blocks,
each one reserved for identifying a group of items with a common characteristic.
Group classification code:
This code type is useful when the item or information to be coded can be broken down into sub
divisions.

The zip code is an example for group classification code.

Significant digit code:

It is a numeric code in which the numbers describe a measurable physical characteristics of the
item.

The characteristics may be length, capacity, size, time or any physical measurable attributes.

For example, tire size

Alpha numeric code:

It describes item by using letter and number combinations.

There are two categories:

1. Mnemonic code
2. Derivation code

Mnemonic codes:

Mnemonic codes are letter and number combinations obtained from descriptions of the coded
items.
Derivation code:

These codes are characters taken or derived from the name of the coded item according to a set
of rules.

They are used to handle large volume list that must be maintained and processed in sequence.

Self-checking code:
Self-checking codes are numeric code to which a check digit has been added to provide a validity
check.

This code is commonly used in automated systems were numeric codes are entered manually.

Example: 12463 - 2

(1*1) + (2*2) + (4*3) + (6*4) + (3*5) = 56

 56 = 5+6 = 11 = 1+1 = 2

Forms design:

Form design follows the process of analysing forms, evaluating documents that are already
present and creating new forms or improving old ones.

Decision trees:

A decision tree is a network type chart that is equivalent to a decision table.

Like a decision table it describes logical rules showing all of the actions that result from various
combinations of conditions.

Valid store ID allow purchase 25k

No valid store ID purchase more than 25k call store manager

purchase less than 20k with 2 other ID allow purchase

without 2 other ID call store manager

Decision table:

Basic format of a decision table contains:

1. Condition stub to list all the conditions to be considered

2. Condition entries to make up rules to be followed
3. Action entries to point to actions that may be taken
4. Action stub which identifies the action to be followed
Structured English:

Structured English uses standard logical terms such as IF, THEN, and ELSE.

For example:

IF valid store identification

THEN
allow purchase+$25
Else
IF purchase more than $20
THEN
call store manager
Else
If two other identifications
THEN
Allow amount of purchase
Else
call store manager

Data flow diagrams (DFD):

A data flow diagram (DFD) is a network that describes the flow of data throughout the system
and also data stores and processes that change or transform data flows.

Data flow diagrams are constructed from four basic symbols. Using these symbols a system
analyst can construct a logic network that traces data stream throughout a system.

A circle or bubble represents a transformation process and label inside the bubble describes the
process.

Data flows are directed lines that identify the input data flows and output data flows at each
process bubble.
Data storage is represented by an open ended rectangle with a label that identifies the data
store or file.

The square is labelled to identify an external entity that is a source or destination of a dataflow.

DFD transformation and decomposition:

The three principal type of data stream transformation that take place at the processing bubble
as follows:

When studying complex situations, data flow diagrams would become much too confusing for
analysts to understand and to work with if all of the significant data flows were drawn as a
single network.

It is best to prepare one data flow diagram that provides an overall picture then to, break the
picture down into a hierarchy of smaller pictures.

Thus, high-level DFDs are sub-divided, or partitioned, into a hierarchy of lower-level DFDs
through a procedure called decomposition.

Data dictionary:
Data elements:

Data elements are the smallest unit of data that is meaningful to the system in which it is used.

Data structure:

Often there are structured relationships between data elements. These relationships are called
data structures.

For example, the data structure “Name” which includes the data elements last name, first name
and initial etc.

A data dictionary is a central repository that defines and describes all of the data structures
with in a system.

System flow chart (SFD):

A system flowchart explains how a system works using a diagram.

A flowchart is a type of diagram that represents an algorithm or process showing the steps as
shapes and connecting these with arrows.

2 types of system flow chart:

1. Information oriented system flow chart

2. Process oriented system flow chart

Information system flow chart:

 Information system flow chart uses a grid structure to trace the flow of data.
 This identifies the input data and follows its flow until an output appears.
 They do not identify the processing operations

Process oriented system flow chart:

 Process oriented system flow charts signifies the data processing operations that
convert input into outputs.
 These flow charts can be drawn at any level of detail.
 The higher level flowcharts are the least detailed flow charts. They are used in study
phase.
 Lower levels of detail are represented by expanded flow charts that are intermediate
flow charts. They are used in design phase
 Detailed level flow charts are used in development phase.

HIPO charts:
 Module 3:

Study phase activities:

The study phase is the first life cycle phase in the process of creating a business information
system or a new system or a modification of an old system.

During the study phase an initial analysis is carried out in sufficient depth to permit a technical
and economical evaluation.

At the conclusion of the study phase a decision is made, whether to proceed the next level or
not.

The diagram of the study phase is shown below:

Study phase
review
User need User review

Performance
specification
Study phase
Information Modified Project report
service request service request directive
Study phase
report
preparation Approval to
Initial proceed
investigation System
performance Feasibility
definition analysis

DESIGN
PHASE
Fig. study phase activities

1. User need:

The creation of computer based business information system begins with a stated user need.

The user may need a requirement for a new information for the solution of the problem they’re
facing.

The statement of needs are a written request for information system service which we shall
refer to complete the needs.

2. Initial investigation:

The first steps in the initial investigations are directed towards clarifying the problem.

Two major activities in this phase are fact finding and fact analysis.
Fact finding includes reviewing existing manuals and procedures, preparing questionnaires and
conducting interviews.

Fact analysis is accomplished by data element analysis, input-output analysis including data flow
diagrams.

If there is an existing system that is performing all of the functions the new system is to
perform, the analyst must study this system.

3. User review:

The modified information service request reveals the analyst to understand the problem and
state the understanding of the system objectives.

The modified information service request is discussed with the user and this becomes the
formal contract between the user and the system analyst. This contract is called projective
directive.

4. System performance definition:

It is the transition from a logical performance requirement to a physical one.

The process include the statement of limitations, identifications of objectives and description of
the outputs to be provided.

5. Feasibility analysis:

It includes evaluating whether or not the creation of the system could be successful.

It helps the user to consider the costs and activities required to set up and run a business.

6. Study phase report:

After the feasibility study has been completed, a study phase report is prepared for the user.

It contains a summary of the feasibility study and present recommendations related to

proceeding with the design phase.

7. Study phase review:

The study phase report is reviewed with the user. If the recommendation of the report is
accepted, the user issues a written approval to proceed.

This approval includes an authorization to proceed and other resource expenditures required
for the design phase.

Fact finding techniques:

Fact finding is process of collection of data and information based on techniques which contain
sampling of existing documents, research, observation, questionnaires and interview.
System analyst uses suitable fact-finding techniques to develop and implement the current
existing system.

Fact-finding techniques are used in the early stage of SDLC such as study phase, design phase.

The fact finding techniques involve:

1. Data collection
2. Questionnaires
3. Interviews
4. Observation
5. Research

Fact analysis techniques:

Fact finding and fact analysis are related activities. The information we obtain from fact finding
is analysed here.

Four fact analysis techniques are,

1. Data element analysis

2. Input-output analysis
3. Recurring data analysis
4. Report use analysis

Feasibility study:

Feasibility study means to check whether the proposed system is proposed or not.

Following are the 4 categories of feasibility study:

1. Operational feasibility is a measure of how well the solution will work in the
organization.

2. Technical feasibility is a measure of the practicality of a specific technical solution and

the availability of technical resource and expertise.

3. Schedule feasibility is a measure of how reasonable the project timetable is.

4. Economic feasibility is a measure of the cost-effectiveness of the system/project and its

solution. This is often called a cost-benefit analysis.

Steps in feasibility analysis:

1. Complete formation of system team

Team should be a group of involved, interested people to help define system problems and
develop methods of solution.

2. Review system data flow diagrams

Data Flow Diagrams allow visualization of physical characteristics of new system.

Reviewing DFD proceeds without difficulty as the team has required sketches and data elements
during system performance definition.

3. Develop system candidates

Develops a candidate systems which can produce output identified in data flow diagrams.

System team helps analyst in brainstorming various hardware combinations.

4. Perform initial evaluation of candidates

Initials evaluation is to narrow down number of system hardware to a manageable number.

Systems which are not practical due to high cost or overkill for task is eliminated.

5. Prepare detailed descriptions of candidates

The fifth step in feasibility analysis is to prepare detailed descriptions of the hardware appearing
in the candidate system.

The detailed descriptions should include flowcharts and narratives, specific constraints,
identified inputs, processing requirements, and storage requirements.

6. Identify meaningful system characteristics

Evaluation of candidates are based on performance and cost.

Performance evaluation relates to accuracy, control capability, flexibility, response time,

storage, growth potential.

Cost evaluation include cost of developing the system and operating it after its implementation.

7. Determine performance and cost for each candidate

Accuracy of a candidate refers to accuracy of system.

Control capability refers to security of the system by protecting from illegal manipulation.

Flexibility refers to ease of adjusting the system.

Growth potential measures the extent of growth of the system without extensive modification
to the system.

Response time refers to total elapsed after the user submitted the input until it gets an output.

Storage requirements refers to main storage as well as auxiliary storage for files.

8. Weigh system performance and cost characteristics

Weighed candidate evaluation is for candidate evaluation entries by their importance and
applies a rating number.

9. Select “best” system

Candidate with highest total score is probably the best system.

Analyst should present to users and management for their acceptance or rejection.

Study phase report:

1. SYSTEM SCOPE
 System title

 Problem statement and purpose

 Constraints

 Specific objectives

 Method of evaluation

2. CONCLUSIONS AND RECOMMENDATIONS

 Conclusions

 Recommendations

3. PERFORMANCE SPECIFICATION
 External performance specification

 Internal performance specification

4. PLANS AND COST SCHEDULES

 Detailed milestones - study phase

 Major milestones - all phases

  Detailed milestones - design phase

5. ADDITIONS

Important topics:

Design phase:
The design phase is the second phase in SDLC. It is the phase where a detailed design of the
computer based system is created.
Logical design:
The logical design specifies the discrete idea about the design. It describes the design
objectives and requirements needed.
Physical design:
The physical design brings the logical design to life by implementation of devices.

Speciality forms:
Speciality forms are different types of forms that system analysts use for different purposes.

Design phase report:

Title page: title of the project, client, date, project team details
Summary:
 Set the problem in context
 Summarize what the analyst have done
 Describing the design solution
 Report on its performance
Table of contents: like an index, using headings, titles and numbered sections.
Introduction: Introducing and defining the problem and the objectives or technical
specifications in context, including constraints of the design.
Analysis section:
 an overview of the design
 design requirements or specifications
 testing procedures and results
 an assessment of the final design and its performance
Conclusion: summarization of the whole the design.

Test plans:
The implementation of a computer system requires tested data to be prepared and the
system and its elements to be tested and planned in a structured manner.
There are two methods of planning for the development and testing of computer programs.
1. Bottom-up method
2. Top-down method

Bottom-up method:
The bottom up methods for developing computer program is based upon proceeding from
lower level modules to higher level modules.
Failure of all those modules collide at the highest level often produced cost overruns and
delayed schedules.
Top-down method:
The top down computer program development and testing approach is a structured
technique that starts with the higher level modules which then are broken down to lower
level modules.
It can be more efficient in terms of decision making and execution.

Training:
Training plans are an important element of the implementation plan.
Their purpose is to ensure all the workers who are associated with the computer based
business system possess the necessary knowledges.
There are three types of trainings:
1. Programmer training
2. Operator training
3. User training

Programmer training:
In programmer training they are assigned a reference manual which enables them to:
 Understand existing program components.
 Modify existing program components.
  Write new program components.

Operator training:
If new equipment is to be installed, operator training is completed with its installation and
checkout.
If new equipment are not to be installed for the computer based system, the users must be
familiar with the operational requirements.
The reference manual for operator training must include: the operators of the system with
its purpose and step by step operating instructions.

User training:
In user training a user reference manual is required, which should explain the system in
terms of user’s specific needs.
The manual should provide the users with a general overview of the system.

Changeover plan:
A changeover plan specifies the transition from old system processes to newly created
system processes.
The 3 general method of it are:
1. Parallel operation
2. Immediate replacement
3. Phased changeover
Parallel operation includes data processing by the old and new systems.
Immediate replacement requiring immediate use of a new system is a risky alternative.
The outputs of the new system is compared with the outputs of the old system to identify
errors.
Phased changeover is a compromise between parallel operation and immediate
replacement. It is recommended over the other two methods.

Structured programming:
It is a top-down approach to the creation of the program.
It is more than a technique used in coding a program. It describes the development of the
program function definition to documentation.
They are made up of series of program modules, each of them performs a single function.
The first module has the most general concept and the following modules have more
detailed concepts.
Structured programming are made up of combinations of only four structures:
1. Sequence
2. If then else
3. Iteration
4. Case

Development phase activities:

Development phase is the third phase of the SDLC. It is the life cycle in which the system is
constructed and designed according to the design specifications.

Implementation planning (includes training of users)

Computer program design (input and output files are identified, flowcharts are created)

User review (it keeps the user informed about the project progress)

Equipment acquisition and installation (hardware that supports the system are identified,
brought and tested)

Coding and debugging (computer program components of the system are coded and
debugged)

Computer program testing

System testing

Reference manual preparation (reference manuals are prepared for training)

 Workers training

Changeover plan (changing the old system to new system)

Development phase report preparation

User acceptance review

Forms:
The task of producing a detailed layout for the forms is the responsibility of the forms
specialist.
Basic parts of a form:
1. Title: title of the form, for example “purchase order”
2. Instructions: set of instructions on how to fill the form.
3. Heading: it includes form name, address and number.
4. Body: specifies the specific data which the form wants.
5. Conclusion: contains approvals, signatures.

Styles of forms:
Two basic styles are the open style and the boxed style forms.
The open style form: it is the simplest form, it consists of headings and open areas to insert
the data.
Boxed style forms: it specifies spaces for each data item to be inserted.

Types of forms:
The types of the forms are classified on the basis of complexity.
The most common forms are printed on a single sheet called cut forms.
Speciality forms are more complex. Examples are forms with special binding and forms
designed to be completed using machines.
There are 4 types of speciality forms:
 1. Forms bound into books: they are the simplest speciality forms. They are designed to
be filled manually.
2. Continuous forms: they are a series of pages attached in a long continuous string.
3. Detachable stub sets: they can be filled in by hand or a machine and one or more
carbon copies are attached to the original copy.
4. Mailers: it is a version of continuous form which can only be printed by machines.

Operation phase:
The operation phase follows the development phase. It is the longest phase of the SDLC.
This phase is called the changeover phase where the new system is implemented or the old
system is modified into a new system.
This phase takes weeks or even months to complete.

Activities in this phase are as follows:

1. System changeover:
If the implementation at the development level has been performed accurately, the
responsibility of the new system is assigned to a trained person
2. Routine operation:
Respective responsibilities are assigned and procedures are established for change control.
3. System performance evaluation:
The result of the evaluation of the new system are documented and the report should be
presented to the performance review board to review it.
4. System change:
The PRB may file a change to the system. The investigations and changes may be lead to
cycling back to the previously completed phase.

Changeover crisis:
After the acceptance review is held at the end of development phase, it assures the user
that the new system was ready for operation but it fails, that is known as changeover crisis.
All of the activities done at the development phase such as implementation planning,
changeover planning fails.

Routine operation:
When the system have been changed and turned over to the user, its routine operation
becomes the responsibility of the data processing department.
The steps of data processing at different departments are:
1. DP-1:
Data processing reports to financial functions and provides programming and machine
supporting reports. (Summary reports)
2. DP-2:
Verifying the reports or summary created at DP-1 is the main responsibility of DP-2 by a
general administrator.

3. DP-3:
The reports verified by the administrator is passed onto a top executive who gives the
approval for the reports.