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 (also called common cause variation):
Natural, inherent fluctuations in a process.
Caused by many small, unavoidable factors.
Expected variation within control limits.
Examples: Slight differences in raw materials, minor temperature fluctuations,
normal human variability.
Nonrandom variation (also called assignable cause variation):
Caused by identifiable, specific factors.
Not part of the process under normal conditions.
Leads to data points outside control limits or unusual patterns.
Examples: Equipment malfunction, untrained operators, defective raw material.
Key Difference: Random variation is always present and cannot be eliminated entirely,
while nonrandom variation indicates a problem that should be investigated and
corrected.
1.2 Discuss the different nonrandom signals that can occur when using a process
control chart to analyse a process. (5 marks)
1. Point outside control limits: Indicates a shift or unusual event.
2. Run of seven (or more) points on one side of the center line: Suggests a
sustained shift in the process.
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 (also called common cause variation):
Natural, inherent fluctuations in a process.
Caused by many small, unavoidable factors.
Expected variation within control limits.
Examples: Slight differences in raw materials, minor temperature fluctuations,
normal human variability.
Nonrandom variation (also called assignable cause variation):
Caused by identifiable, specific factors.
Not part of the process under normal conditions.
Leads to data points outside control limits or unusual patterns.
Examples: Equipment malfunction, untrained operators, defective raw material.
Key Difference: Random variation is always present and cannot be eliminated entirely,
while nonrandom variation indicates a problem that should be investigated and
corrected.
1.2 Discuss the different nonrandom signals that can occur when using a process
control chart to analyse a process. (5 marks)
1. Point outside control limits: Indicates a shift or unusual event.
2. Run of seven (or more) points on one side of the center line: Suggests a
sustained shift in the process.
