MANAGEMENT INFORMATION SYSTEMS
Chapter 6:
Chapter 6
Tools For Determining System Requirements
And System Analysis
6.1 Learning Outcomes
After complete this lesson, you would be able to:

Discuss about decision tree and its advantages.

Know when could you use decision table.

Explain the advantages and disadvantages of structured English.

Illustrate the steps of to do decision table.
6.2 Tools For Requirement Specification

There exist lots of tools that could be used in helping SA to
perform the analysis tasks.

All these tools are to ensure that the tasks of analysis are performed
with accuracy and efficiency.

Some of these tools include: - Decision Tree
- Decision Table
- Structured English
6.2.1 Decision Tree

It is a graphical tool that used to represent conditions and their
respective result actions.

Used when complex branching occurs in a structured decision
process.

It is essential to keep a string of decision in a particular process.

The root of the tree is on the left-hand side, branching out to the
right. This orientation allows the analyst to write on the branches
in order to describe conditions and actions.

The sequence of the condition and actions are important. We begin
to build the tree from left to right while making sure that we
complete listing all possible alternatives before moving over to the
right.

It is useful to distinguish between conditions and actions when
drawing decision trees. Uses a square node to indicate an action
while a circle to represent a condition. Also, use of notation to
make the decision tree more readable. Think of a circle as
signifying IF while the square means THEN.

A tree might not always be symmetrical all the times, where we
could have a complex decision tree.
TOOLS FOR DETERMINING SYSTEM REQUIREMENTS AND SYSTEM ANALYSIS
Page 1 of 9
MANAGEMENT INFORMATION SYSTEMS
Chapter 6
The steps involved in building a decision tree: - Identify the conditions
- Identifies the condition alternatives
- Identify the actions
- Identify action rules (enter actions)
- Create key and title
Advantages of using decision trees:

The order of checking conditions and executing actions is
immediately noticeable.

Conditions and actions of decision trees are found on some
branches but not on others, unlike decision tables where they are all
part of the same table.

Those conditions and actions that are connected directly to other
conditions and actions, while those conditions that do not matter
are absent.

Compared to decision tables, decision trees are more readily
understood by others in the organization. Thus, they are more
appropriate as a communication tools.
Disadvantages of decision trees:

Disadvantages of decision tree are taking up space and
consequently a minimum amount of description on the conditions
and actions can be written on the trees.
Example of decision tree:
Bad
Payment
Rating
Has
Account
No
Account
4
Credit
Allowed
Manager
Disapprove
5
Credit
Disallowed
3
2
Good
Payment
Rating
1
Manager
Approve
6
7
TOOLS FOR DETERMINING SYSTEM REQUIREMENTS AND SYSTEM ANALYSIS
Credit
Allowed
Credit
Disallowed
Page 2 of 9
MANAGEMENT INFORMATION SYSTEMS
Chapter 6
6.2.2 Decision Table

A decision table is a table of rows and columns, separated into four
quadrants.
Conditions
Condition
Alternatives
Actions
Action Entries

In order to build a decision table, the analyst needs to determine the
maximum size of the table, eliminate any impossible situations,
inconsistencies or redundancies and simplify the table as mush as
possible.
The steps of building a decision tables are as follows: 1.
Determine the number of conditions that may affect the decision.
2.
Determine the number of possible actions that can be taken.
3.
Determine the number of condition alternatives for each condition.
4.
Calculate the maximum number of columns in the decision table
by multiplying the number of alternatives for each condition.
5.
Fill in the condition alternatives.
6.
Complete the table by inserting an ‘X’ where rules suggest certain
actions.
7.
Create a key to explain the abbreviations, if any.
8.
Apply combine rules, where it is apparent that an alternative does
not make a difference in the outcome.
9.
Condition 1: Y
Y
Condition 1: Y
Condition 2: Y
N
Condition 2: – (can be ‘Y’ or ‘N’)
Action 1: X
X
Action 1: X
Action 2:
Action 2:
10.
Check the table for any impossible situation, contradiction and
redundancies.
Conditions
And Actions
Salary > RM 50,000/year
Salary < RM 2,000/month
Action 1
Action 2
Rules
1
2
Y
Y
Y
N
3
N
Y
4
N
N
This is an impossible
situation
TOOLS FOR DETERMINING SYSTEM REQUIREMENTS AND SYSTEM ANALYSIS
Page 3 of 9
MANAGEMENT INFORMATION SYSTEMS
Conditions
And Actions
Condition 1
Condition 2
Condition 3
Action 1
Action 2
Action 3
Rules
1
Y
Y
X
2
Y
Y
N
Chapter 6
3
Y
Y
-
4
Y
N
X
5
Y
N
X
6
N
Y
N
X
X
X
X
Contradiction


11.
7
N
N
Y
Redundancy
Contradictions occur when rules suggest different actions but
satisfy the same conditions. Contradictions often occur if the
dashes (-) are incorrectly inserted into the table.
Contradictions could also be a result of discrepant information
gathered from different systems users. Redundancy occurs when
identical sets of alternatives require the exact same action.
Rearrange the condition and actions if this makes the decision table
more understandable.
Decision table sample
Conditions
And Actions
Raining Days
Weekend
Stay at home
Go to neighbor’s house
Go shopping with friends
Conditions
And Actions
Raining Days
Weekend
Stay at home
Go to neighbour’s house
Go shopping with friends
Rules
1
2
Y
Y
Y
N
X
X
3
N
Y
4
N
N
X
X
Rules
1
2
Y
Y
N
X
X
3
N
Y
X
TOOLS FOR DETERMINING SYSTEM REQUIREMENTS AND SYSTEM ANALYSIS
Page 4 of 9
MANAGEMENT INFORMATION SYSTEMS
Chapter 6
Enhanced decision tables
Decision tables can become very burdensome because they grow
rapidly as the number of conditions and alternatives increase.
For instance, a table with only seven conditions would have 128
columns.
Use of extended entries, ELSE rule or construct multiple tables
could resolve this situation.
Extended-Entry Form
A narrative action approach is used instead of simply a Y or N in
the case of a limited-entry form table.
Conditions
And Actions
Staff Member
Associate Member
Master Student Member
Other Member
Maximum 2 borrowed books
Maximum 4 borrowed books
No limit of borrowed books
Conditions
And Actions
Types of membership
Maximum borrowed books
1
Y
N
N
N
Rules
2
3
N
N
Y
N
N
Y
N
N
X
X
4
N
N
N
Y
X
X
Rules
Staff
No
limit
Associate master
4
2
others
2
ELSE-Entry Form
This form is useful in helping to eliminate many repetitious rules
requiring the same exact action. It is also useful in preventing
errors of omission.
Conditions
And Actions
Types of membership
Maximum borrowed books
Rules
Staff
No limit
Associate
4
TOOLS FOR DETERMINING SYSTEM REQUIREMENTS AND SYSTEM ANALYSIS
ELSE
2
Page 5 of 9
MANAGEMENT INFORMATION SYSTEMS
Chapter 6
Multiple Tables
Multiple tables are used to control the size of the table.
Conditions
And Actions
Book is lost
Returned book is damaged
Book us overdue
Stamp ‘Cancel’ on the date-due
PERFORM TABLE B
Charge price of book
Issue an official receipt
Conditions
And Actions
Overdue less than 30 days
Overdue more than 30 days
Staff/associate member
Fine 10 cents per day
Fine 20 cents per day
Fine $10
RETURN
1
2
Rules
3
4
5
N
Y
Y
X
X
X
Rules
1
2
3
4
5
Y
N
Y
X
X
Case:

Suppose you have to get up at around 8am if you are going to get
work on time. You go to work on Monday to Friday only and have
your weekends free.

If you woke up on Tuesday morning at 8:05am, you would be
faced with the following appalling dilemma where you will be late
for work. An X marks the actions you should take where you are
either stay in bed or wake up.
6.2.3 Structured English

Many functional operations simply involve straightforward
sequence of tasks or the iteration of smaller operations. In such
case, a series of concise English statements, called Structured
English, can be used to communicate the processing rules.

It is a Standard English that similar to pseudocode of the structured
programming.

Users are generally comfortable with English statements. As the
format of structured English is sufficiently precise so that it will
not be misinterpreted by designers or programmers.
TOOLS FOR DETERMINING SYSTEM REQUIREMENTS AND SYSTEM ANALYSIS
Page 6 of 9
MANAGEMENT INFORMATION SYSTEMS

Chapter 6
A Structured English must conform to the following rules:
(i). Use only the 3 building blocks of sequence, selection and
iteration.
(ii). Use indentation for readability
(iii). Use a limited vocabulary including standard terms used in the
data dictionary and specific words that describe the processing
rules.
Three basic constructs of Structured English are:
1. Sequence
 The completion of one of two steps in sequential order, one after
another.
 One or more of the steps might represent a sub process that
contains additional logical structures.
Verify
Product Code
Verify Price
Verify Stock
Level
 Example:
Request the borrower’s library card.
Check the borrower is the owner of the card.
Receive the books from the borrower.
Check the books are non-reference materials.
Stamp due dates on the books.
Return the library card and the stamped books to the
borrower.
2. Selection
 Often, we need to make decision where the successive actions are
based on certain decision made.
 Two possible forms are the IF-THEN-ELSE-ENDIF form and
CASE-OTHERWISE-ENDCASE form.
 IF-THEN-ELSE-ENDIF form is probably easier for the user to
understand when there are only two options possible for the
selection. Use of indentation and the separation of lines will
enhance the readability.
 When three or more options are possible for a selection, the CASEOTHERWISE-ENDCASE construct usually communicates better.
TOOLS FOR DETERMINING SYSTEM REQUIREMENTS AND SYSTEM ANALYSIS
Page 7 of 9
MANAGEMENT INFORMATION SYSTEMS
Hours
> 40?
Chapter 6
Yes
Calculate
Overtime Pay
No
 The system that test the input and if the hours are greater then 40, it
performs the “Calculate Overtime Pay” process.
 Example:
IF the books are overdue
THEN Compute the overdue fine.
Collect the fine from the borrower.
Issue a receipt.
Return the books to the shelves.
ELSE Return the books to the shelves.
ENDIF
Identify the category of the books
CASE(Artificial Intelligent category)
Label the book index with prefix ‘AI’
CASE (Database category)
Label the book index with prefix ‘DB’
CASE (Programming category)
Label the book index with prefix ‘PG’
OTHERWISE
Label the book index with prefix ‘XX’
ENDCASE
3. Iteration / Repetition
 It shows the repetition of a group of statements some number of
times until it is done (or met some condition).
 The group of statements to be repeated is indented directly below
the conditional statement. The condition statement specifies the
number of times the iteration is to occur.
TOOLS FOR DETERMINING SYSTEM REQUIREMENTS AND SYSTEM ANALYSIS
Page 8 of 9
MANAGEMENT INFORMATION SYSTEMS
Chapter 6
 It has three possible forms: FOR-ENDFOR, DO WHILE- ENDDO
and REPEAT-UNTIL.
End of
file?
No
Print
Paycheck
Yes
 Example:
FOR each purchased book
Check the title matches with the invoice statements.
Browse through the book to ensure no torn pages.
IF the book is torn
THEN
Reject the book.
ENDIF
ENDFOR
DO WHILE there are unpacked books
Check the book is not torn.
Return the book to appropriate book shelves.
ENDDO
REPEAT
Create an overdue reminder letter for the member.
Mail the letter to the reminder.
UNTIL no more overdue cases.
Review Questions
1.
What is decision tree?
2.
What are the advantages of decision tree?
3.
Explain the advantages and disadvantages of structured English.
4.
What are the steps to do decision table?
TOOLS FOR DETERMINING SYSTEM REQUIREMENTS AND SYSTEM ANALYSIS
Page 9 of 9