MNO2602
ASSIGNMENT 4 SEMESTER 1 2025
UNIQUE NO.
DUE DATE: MAY 2025
, MNO2602 Assignment 4 – Semester 1, 2025
Question 1 [16 marks]
1.1 Distinguish between random variation and nonrandom variation in a process.
(6 marks)
Random variation (Common Cause):
o Inherent in the process.
o Caused by unknown factors that are always present.
o Typically small and follow a predictable pattern.
o Cannot be eliminated, only reduced.
o Example: minor differences in temperature or humidity.
Nonrandom variation (Assignable Cause):
o Arises due to specific identifiable causes.
o Unpredictable and not inherent in the system.
o Indicates something has changed in the process.
o Can be corrected or eliminated.
o Example: machine malfunction or operator error.
1.2 Discuss the different nonrandom signals that can occur when using a process
control chart. (5 marks)
Point outside control limits: Indicates a special cause of variation.
Run of points on one side of the centerline: May indicate a shift in the process
mean.
Trends (continuous increase or decrease): Suggest gradual change in the
process.
Cycles or periodic patterns: May indicate systematic influences.
Two out of three points near a control limit: A potential signal of instability.
ASSIGNMENT 4 SEMESTER 1 2025
UNIQUE NO.
DUE DATE: MAY 2025
, MNO2602 Assignment 4 – Semester 1, 2025
Question 1 [16 marks]
1.1 Distinguish between random variation and nonrandom variation in a process.
(6 marks)
Random variation (Common Cause):
o Inherent in the process.
o Caused by unknown factors that are always present.
o Typically small and follow a predictable pattern.
o Cannot be eliminated, only reduced.
o Example: minor differences in temperature or humidity.
Nonrandom variation (Assignable Cause):
o Arises due to specific identifiable causes.
o Unpredictable and not inherent in the system.
o Indicates something has changed in the process.
o Can be corrected or eliminated.
o Example: machine malfunction or operator error.
1.2 Discuss the different nonrandom signals that can occur when using a process
control chart. (5 marks)
Point outside control limits: Indicates a special cause of variation.
Run of points on one side of the centerline: May indicate a shift in the process
mean.
Trends (continuous increase or decrease): Suggest gradual change in the
process.
Cycles or periodic patterns: May indicate systematic influences.
Two out of three points near a control limit: A potential signal of instability.
