Chapter 7

Question 1

Why is process modelling studied?

Answer 1

• to communicate business process and design
• Modelling standardises our design
• Modelling allows us to better understand the processes
• Models allow us to improve processes

Question 2

What are data flow diagrams?

Answer 2

Graphically characterize data processes and flows in a business system

Question 3

What do data flow diagrams (DFDs) depict?

Answer 3

System inputs
Processes
Outputs

Question 4

advantages of the data flow approach

Answer 4

• Freedom from committing to the technical implementation too early
• Understanding the interrelatedness of systems and subsystems
• Communicating current system knowledge to users
• Analysis of proposed system

Question 5

What is a context diagram?

Answer 5

• Highest level in the data flow diagram
• Contains only one process that represents the entire system
• Process is given the number 0
• All external entities and data flows are shown

Question 6

What is diagram 0?

Answer 6

• Explosion of the context diagram
• Can include up to 9 processes
• Each process is numbered
• All data stores and external entities are included

Question 7

What is a child diagram?

Answer 7

• An explosion of a process on diagram 0
• Cannot produce output or receive input that the parent process does not also
  receive or output

Question 8

Common data flow diagram errors

Answer 8

• Forgetting to include data flow
• Arrow pointing in one direction
• Connecting data flows and external entities to each other
• Incorrectly labelling processes or data flow
• Including more than 9 processes
• Creating unbalanced decomposition in child diagrams
• No data processing (input of process = output of process)
• Process has no input
• Process has no output
• Two data stores are connected

Question 9

Logical Data Flow Diagram (DFD)

Answer 9

• Focuses on the business and how it operates
• Not concerned with how the system will be constructed
• Describes business events that take place and the data required and
  produced by each event

Question 10

Physical Data Flow Diagram (DFD)

Answer 10

shows how the system will be implemented

Question 11

Progression of models from logical to physical

Answer 11

1. Current logical data flow diagram
   - Derive the logical DFD by examining physical DFD and isolating unique business activities
2. New logical data flow diagram
   - Create logical DFD by adding input, output and processes required in the new system to the logical DFD
3. New physical DFD
   - Derive physical DFD by examining processes on the new logical diagram.
   - Determine where user interfaces should exist, nature of processes and data stores

Question 12

Benefits of developing logical data flow diagrams

Answer 12

• Better communication with users
• More stable system
• Better understanding of business by analysts
• Flexibility and maintenance
• Elimination of redundancy and easier creation of physical model

Question 13

CRUX matrix: what does CRUD stand for?

Answer 13

C: create
R: read
U: update
D: delete

Question 14

CRUX matrix

Answer 14

• Activities present in a system for each master file

- A tool to represent where each of these processes occurs in a system

Question 15

Partitioning Data flow diagrams

Answer 15

• Process of examining a data flow diagram and determining how it should be divided into collections of manual procedures and computer programs
• Dashed line is drawn around a process/group of processes