Quality Management Tools: Statistical Process Control | MCQ

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Top 100+ MCQs on Quality Management Tools: Statistical Process Control for MBA Exams

1. Basics of Statistical Process Control (SPC)

Which of the following is a primary objective of Statistical Process Control (SPC)?
a) Eliminate variability
b) Monitor and control processes
c) Replace manual operations
d) None of the above
Answer: b) Monitor and control processes

In SPC, what does a control chart primarily help detect?
a) Process specifications
b) Special cause variations
c) Average product cost
d) Standard time deviation
Answer: b) Special cause variations

What is the fundamental assumption of SPC?
a) Processes are always under control
b) Variability is unavoidable
c) Processes exhibit inherent variability
d) None of the above
Answer: c) Processes exhibit inherent variability

2. Components of Control Charts

Which of the following is not a component of a control chart?
a) Control limits
b) Center line
c) Specification limit
d) Process mean
Answer: c) Specification limit

What does the centerline in a control chart represent?
a) The upper control limit
b) The lower control limit
c) The average of the process
d) The process specification
Answer: c) The average of the process

Control limits on a control chart are set at typically how many standard deviations from the center line?
a) 1 sigma
b) 2 sigma
c) 3 sigma
d) 4 sigma
Answer: c) 3 sigma

3. Types of Control Charts

Which control chart is best suited for monitoring the number of defects in a sample?
a) X-bar chart
b) p-chart
c) c-chart
d) R-chart
Answer: c) c-chart

Which type of control chart is used for monitoring continuous data?
a) p-chart
b) np-chart
c) X-bar and R charts
d) c-chart
Answer: c) X-bar and R charts

The p-chart is used to monitor which type of data?
a) Continuous data
b) Attribute data (proportion of defectives)
c) Count data
d) None of the above
Answer: b) Attribute data (proportion of defectives)

4. Process Control and Capability

What is meant by “process capability”?
a) The ability of a process to meet customer requirements
b) The ability of a process to remain within control limits
c) The ability of a process to eliminate defects
d) None of the above
Answer: a) The ability of a process to meet customer requirements

A process is said to be under statistical control if:
a) There are no variations in the process
b) Only common cause variations are present
c) There are no defects in the product
d) Special cause variations exist
Answer: b) Only common cause variations are present

Which of the following is used to assess process capability?
a) Process Control Chart
b) Capability Indices (Cp and Cpk)
c) Histogram
d) Scatter Diagram
Answer: b) Capability Indices (Cp and Cpk)

5. SPC Tools and Techniques

Which SPC tool is used to visualize the frequency distribution of data?
a) Scatter diagram
b) Histogram
c) Pareto chart
d) Fishbone diagram
Answer: b) Histogram

The Pareto principle used in SPC suggests that:
a) 20% of causes result in 80% of problems
b) 50% of causes result in 50% of problems
c) All causes contribute equally to problems
d) None of the above
Answer: a) 20% of causes result in 80% of problems

A fishbone diagram is also known as:
a) Cause-and-effect diagram
b) Pareto chart
c) Scatter plot
d) Histogram
Answer: a) Cause-and-effect diagram

6. Practical Applications of SPC

What does an out-of-control process indicate in SPC?
a) Random variation
b) Special cause variation
c) Common cause variation
d) Stable process
Answer: b) Special cause variation

In SPC, when should corrective action be taken?
a) When points fall outside control limits
b) When all points are within limits
c) When data exhibits random variation
d) None of the above
Answer: a) When points fall outside control limits

Which of the following is a common application of SPC in manufacturing?
a) Process improvement
b) Product design
c) Marketing analysis
d) Financial forecasting
Answer: a) Process improvement

7. Advanced Topics in SPC

What does a run of 7 points on one side of the centerline in a control chart indicate?
a) The process is under control
b) A systematic shift in the process
c) Random variation
d) None of the above
Answer: b) A systematic shift in the process

Which chart monitors the variability of a process?
a) X-bar chart
b) R-chart
c) p-chart
d) c-chart
Answer: b) R-chart

8. Real-Life Applications of SPC

SPC is most commonly used in which of the following industries?
a) Healthcare
b) Manufacturing
c) Banking
d) Education
Answer: b) Manufacturing

Which quality improvement methodology heavily relies on SPC?
a) Total Quality Management (TQM)
b) Lean Manufacturing
c) Six Sigma
d) Agile Methodology
Answer: c) Six Sigma

In healthcare, SPC can be applied to:
a) Monitor infection rates
b) Control inventory levels
c) Improve staffing schedules
d) Increase patient satisfaction
Answer: a) Monitor infection rates

How can SPC benefit service industries like banking?
a) By monitoring daily cash flow variability
b) By controlling waiting times in queues
c) By analyzing transaction error rates
d) All of the above
Answer: d) All of the above

The term “assignable cause” in SPC refers to:
a) Variations due to natural process limits
b) Variations due to identifiable external factors
c) Both a and b
d) None of the above
Answer: b) Variations due to identifiable external factors

9. Control Chart Interpretation

What does it mean if data points are trending upward on a control chart?
a) The process mean has shifted
b) Random variation is present
c) The process variability has decreased
d) None of the above
Answer: a) The process mean has shifted

Which of the following would indicate an out-of-control process?
a) 3 consecutive points near the centerline
b) 8 consecutive points on one side of the centerline
c) A random distribution of points
d) All points within control limits
Answer: b) 8 consecutive points on one side of the centerline

In an X-bar chart, if the sample size increases, what happens to the control limits?
a) They widen
b) They narrow
c) They remain the same
d) None of the above
Answer: b) They narrow

10. Advanced SPC Calculations

For an X-bar chart, how is the control limit calculated?
a) Xˉ±3s \bar{X} \pm 3s
b) Xˉ±A2R \bar{X} \pm A_2R
c) 3×R-bar3 \times \text{R-bar}
d) None of the above
Answer: b) Xˉ±A2R \bar{X} \pm A_2R

The process mean is 50, and the standard deviation is 2. What are the control limits at 3 sigma?
a) 44 and 56
b) 46 and 54
c) 48 and 52
d) 40 and 60
Answer: b) 46 and 54

If Cp (Process Capability Index) is 1.5, what does it indicate about the process?
a) The process is incapable
b) The process is capable and exceeds specifications
c) The process is marginally capable
d) None of the above
Answer: b) The process is capable and exceeds specifications

11. Capability Index and Problem-Solving

Calculate Cp for a process with USL = 100, LSL = 50, and σ=10\sigma = 10 :
a) 1.0
b) 1.33
c) 1.5
d) 2.0
Answer: b) 1.33
Explanation: Cp= USL−LSL6σ = 100−506×10 =1.33 Cp = \frac{USL - LSL}{6\sigma} = \frac{100 - 50}{6 \times 10} = 1.33

If Cp is greater than 1 but Cpk is less than 1, what does it suggest?
a) The process is centered but not capable
b) The process is capable but not centered
c) The process is both capable and centered
d) None of the above
Answer: b) The process is capable but not centered

12. SPC Integration with ISO Standards

ISO 9001 emphasizes which aspect of SPC in quality management systems?
a) Elimination of defects
b) Process monitoring and improvement
c) Strict adherence to specifications
d) Reduction in costs
Answer: b) Process monitoring and improvement

SPC contributes to continuous improvement by:
a) Reducing process costs
b) Identifying variations in real time
c) Eliminating customer complaints
d) Automating manufacturing processes
Answer: b) Identifying variations in real time

13. Advanced Problem Scenarios

A process with Cp = 0.8 indicates:
a) The process is incapable of meeting specifications
b) The process is operating within control limits
c) The process has negligible variations
d) The process exceeds specifications
Answer: a) The process is incapable of meeting specifications

For a process with an LSL of 40 and a USL of 80, if the process mean shifts to 70, what is the likely outcome?
a) Increased defect rate
b) Reduced variation
c) No impact
d) Improved capability index
Answer: a) Increased defect rate

If an SPC chart shows a zigzag pattern within control limits, it suggests:
a) Random variation
b) Special cause variation
c) Over-adjustment of the process
d) None of the above
Answer: c) Over-adjustment of the process

14. Problem-Solving with Control Charts

Which of the following is NOT a purpose of using control charts?
a) Detecting trends in the process
b) Reducing the cost of production
c) Monitoring process stability
d) Identifying special causes of variation
Answer: b) Reducing the cost of production

An R-chart is used to:
a) Monitor process variability
b) Track process averages
c) Measure product dimensions
d) None of the above
Answer: a) Monitor process variability

Given an X-bar chart with Xˉ=25 \bar{X} = 25 , R = 5, and A2 = 0.577, what are the upper and lower control limits?
a) 27.89 and 22.11
b) 30 and 20
c) 28 and 22
d) None of the above
Answer: a) 27.89 and 22.11
Explanation: UCL=Xˉ+A2×R=25+0.577×5 = 27.89 UCL = \bar{X} + A2 \times R = 25 + 0.577 \times 5 = 27.89 , LCL=Xˉ−A2×R=25−0.577×5 = 22.11 LCL = \bar{X} - A2 \times R = 25 - 0.577 \times 5 = 22.11 .

What is the main limitation of control charts?
a) They are costly to implement
b) They do not identify the cause of variation
c) They cannot detect random variation
d) None of the above
Answer: b) They do not identify the cause of variation

In an X-bar chart, if the UCL and LCL are very close to the centerline, it suggests:
a) High variability
b) Small sample size
c) Improved process capability
d) None of the above
Answer: b) Small sample size

15. SPC Tools in Practice

Which SPC tool visually identifies the most significant factors in a process?
a) Histogram
b) Pareto Chart
c) Scatter Diagram
d) Control Chart
Answer: b) Pareto Chart

A fishbone diagram is also known as:
a) Ishikawa diagram
b) Root cause analysis diagram
c) Cause-and-effect diagram
d) All of the above
Answer: d) All of the above

Which tool is best for identifying the relationship between two variables in SPC?
a) Scatter Diagram
b) Pareto Chart
c) Control Chart
d) Histogram
Answer: a) Scatter Diagram

A histogram is used in SPC to:
a) Display the frequency distribution of data
b) Monitor process stability
c) Show cumulative frequency
d) Control variability in production
Answer: a) Display the frequency distribution of data

Which tool in SPC highlights whether processes follow the 80/20 rule?
a) Pareto Chart
b) Scatter Diagram
c) Histogram
d) X-bar Chart
Answer: a) Pareto Chart

16. Advanced Case Studies

A process shows a shift in the control chart after a machine adjustment. This is an example of:
a) Random variation
b) Special cause variation
c) Over-adjustment
d) None of the above
Answer: b) Special cause variation

In a Pareto analysis of customer complaints, what should be addressed first?
a) The category with the highest frequency
b) The category with the lowest frequency
c) All categories equally
d) The category causing the most profit loss
Answer: a) The category with the highest frequency

A bakery tracks the weight of loaves using SPC. If the UCL = 600g, LCL = 400g, and the process averages 450g, what does a loaf weighing 650g indicate?
a) Random variation
b) In-control process
c) Special cause variation
d) Normal fluctuation
Answer: c) Special cause variation

17. Advanced SPC Calculations

The standard deviation ( σ\sigma ) of a process is 2, and the process target is 50. What is the Cp for USL = 55 and LSL = 45?
a) 1.0
b) 0.83
c) 1.25
d) 1.5
Answer: a) 1.0
Explanation: Cp= USL−LSL6σ = 55−456×2 =1.0 Cp = \frac{USL - LSL}{6\sigma} = \frac{55 - 45}{6 \times 2} = 1.0 .

A process has Cp = 1.2 and Cpk = 0.8. What does this suggest?
a) The process is not centered but is capable
b) The process is centered but not capable
c) The process is neither centered nor capable
d) The process is capable and centered
Answer: a) The process is not centered but is capable

A sample of 5 items has measurements: 10, 12, 14, 16, 18. Calculate the range (R):
a) 5
b) 7
c) 8
d) 9
Answer: c) 8
Explanation: R=Maximum−Minimum=18−10=8 R = \text{Maximum} - \text{Minimum} = 18 - 10 = 8 .

18. Comprehensive Case Studies

A company implements SPC and finds out-of-control signals on its chart. What should be the first step?
a) Shut down the process
b) Investigate for special causes of variation
c) Adjust control limits
d) Discard the defective units
Answer: b) Investigate for special causes of variation

The Cp value is less than 1.0. What does this mean?
a) The process is meeting specifications
b) The process variability exceeds specification limits
c) The process is improving
d) None of the above
Answer: b) The process variability exceeds specification limits

When should SPC tools be introduced in a new process?
a) During initial process setup
b) After a defect occurs
c) Only after achieving stability
d) None of the above
Answer: a) During initial process setup

19. Conceptual MCQs

Which chart type is best suited for monitoring defective products in a batch?
a) X-bar Chart
b) R-Chart
c) P-Chart
d) C-Chart
Answer: c) P-Chart

What is the primary difference between X-bar and R-chart?
a) X-bar monitors averages; R monitors variability
b) X-bar monitors variability; R monitors averages
c) Both monitor averages
d) Both monitor variability
Answer: a) X-bar monitors averages; R monitors variability

20. SPC Integration with Six Sigma

In Six Sigma methodology, SPC primarily helps in:
a) Identifying defects after production
b) Measuring and controlling process variability
c) Improving employee productivity
d) Reducing production costs directly
Answer: b) Measuring and controlling process variability

The goal of Six Sigma is to achieve a defect rate of:
a) 3.4 defects per million opportunities (DPMO)
b) 10 defects per thousand opportunities
c) 6 defects per million opportunities
d) Zero defects
Answer: a) 3.4 defects per million opportunities (DPMO)

What does DMAIC stand for in Six Sigma?
a) Design, Measure, Analyze, Improve, Control
b) Define, Measure, Analyze, Improve, Control
c) Define, Measure, Assess, Improve, Control
d) Design, Monitor, Assess, Improve, Control
Answer: b) Define, Measure, Analyze, Improve, Control

In SPC and Six Sigma, which tool is used to identify root causes?
a) Control Chart
b) Fishbone Diagram
c) Histogram
d) P-Chart
Answer: b) Fishbone Diagram

How does SPC complement the Measure phase of DMAIC?
a) By improving process designs
b) By tracking process stability and variation
c) By setting customer requirements
d) By eliminating waste
Answer: b) By tracking process stability and variation

21. Lean Manufacturing and SPC

In Lean Manufacturing, SPC helps to:
a) Eliminate defects and waste
b) Increase inventory levels
c) Improve employee retention
d) None of the above
Answer: a) Eliminate defects and waste

Which Lean principle aligns closely with the use of SPC?
a) JIT (Just-In-Time) production
b) Continuous improvement (Kaizen)
c) Increased batch sizes
d) Fixed work procedures
Answer: b) Continuous improvement (Kaizen)

What is a common Lean SPC metric for defect tracking?
a) Defects per unit (DPU)
b) Units per hour (UPH)
c) Total cost of ownership (TCO)
d) Net present value (NPV)
Answer: a) Defects per unit (DPU)

Using SPC to reduce variability aligns with which Lean goal?
a) Reducing lead times
b) Achieving predictable processes
c) Maximizing inventory levels
d) None of the above
Answer: b) Achieving predictable processes

Lean and SPC both aim to:
a) Increase waste to improve efficiency
b) Ensure high process variability
c) Create value for customers by reducing defects
d) Replace human workers with machines
Answer: c) Create value for customers by reducing defects

22. Advanced Statistical Tools in SPC

What is the primary difference between Cp and Cpk in process capability analysis?
a) Cp considers centering, while Cpk does not
b) Cp measures potential capability; Cpk measures actual capability
c) Cp measures actual capability; Cpk measures future capability
d) Both are the same
Answer: b) Cp measures potential capability; Cpk measures actual capability

In a normal distribution, approximately what percentage of data falls within ±3σ?
a) 68.27%
b) 95.45%
c) 99.73%
d) 100%
Answer: c) 99.73%

What statistical tool is used in SPC to test whether a process mean has shifted?
a) T-test
b) ANOVA
c) Control Chart
d) Scatter Plot
Answer: c) Control Chart

In SPC, the term “Western Electric Rules” refers to:
a) Guidelines for constructing control charts
b) Rules for identifying out-of-control processes
c) Methods to calculate Cp and Cpk
d) None of the above
Answer: b) Rules for identifying out-of-control processes

Which SPC technique is most suitable for attributes data?
a) X-bar Chart
b) R-Chart
c) P-Chart
d) Control limits
Answer: c) P-Chart

23. Real-World Applications of SPC

SPC is applied in the service sector primarily to:
a) Improve customer satisfaction by reducing service time variability
b) Measure machine performance
c) Increase batch production
d) None of the above
Answer: a) Improve customer satisfaction by reducing service time variability

In healthcare, SPC is used to:
a) Reduce patient wait times
b) Monitor surgical success rates
c) Track infection rates
d) All of the above
Answer: d) All of the above

Which control chart is most appropriate for monitoring call center wait times?
a) X-bar Chart
b) R-Chart
c) I-MR Chart
d) P-Chart
Answer: c) I-MR Chart

What SPC tool is often used in logistics to reduce delays?
a) Fishbone Diagram
b) Scatter Diagram
c) Pareto Chart
d) Control Chart
Answer: d) Control Chart

24. Miscellaneous and Conceptual MCQs

The main assumption in SPC is that:
a) Processes are inherently stable
b) Special causes of variation dominate
c) Common causes of variation dominate
d) All processes are predictable
Answer: c) Common causes of variation dominate

What is the role of the centerline in a control chart?
a) Represents the target value
b) Shows the average process performance
c) Indicates special cause variations
d) None of the above
Answer: b) Shows the average process performance

If a process produces 5 defects per million units, it is operating at:
a) Below Six Sigma
b) Six Sigma level
c) Above Six Sigma level
d) None of the above
Answer: b) Six Sigma level

25. SPC and Numerical Calculations

For a process with a mean of 100 and a standard deviation of 5, what are the control limits for a ±3σ range?
a) 95 to 105
b) 85 to 115
c) 90 to 110
d) 80 to 120
Answer: b) 85 to 115

A control chart has an upper control limit (UCL) of 200 and a lower control limit (LCL) of 150. The process mean is:
a) 150
b) 175
c) 200
d) Cannot be determined
Answer: b) 175

If the average defect rate for a process is 4%, what is the central line for the P-chart?
a) 0.02
b) 0.04
c) 0.06
d) 0.08
Answer: b) 0.04

For a subgroup sample size of 5, the average range is calculated as 6. What is the UCL for the R-chart if D4 = 2.11?
a) 6
b) 12.66
c) 18.33
d) 10.11
Answer: b) 12.66

26. Special Cause Identification

If 8 consecutive points are above the centerline in a control chart, it suggests:
a) Random variation
b) Common cause variation
c) Special cause variation
d) A stable process
Answer: c) Special cause variation

A single point above the UCL in a control chart indicates:
a) The process is stable
b) Special cause variation
c) Random variation
d) None of the above
Answer: b) Special cause variation

Which of the following patterns suggests an out-of-control process?
a) Points randomly distributed within control limits
b) 5 consecutive points trending upward
c) No points beyond the UCL or LCL
d) None of the above
Answer: b) 5 consecutive points trending upward

27. Attributes Control Charts

A C-chart is used to monitor:
a) The proportion of defects in a sample
b) The number of defects per unit
c) The average number of defects across samples
d) The variability within subgroups
Answer: b) The number of defects per unit

For an NP-chart, the parameter to be monitored is:
a) Number of defective items in a sample
b) Percentage of defects in a population
c) Average range of sample data
d) Total variation in the process
Answer: a) Number of defective items in a sample

If the average defect count per sample is 3, what is the centerline of the C-chart?
a) 1.5
b) 3
c) 6
d) None of the above
Answer: b) 3

28. Process Capability Analysis

A Cp value of less than 1 indicates:
a) The process is capable
b) The process is not capable
c) The process is centered
d) None of the above
Answer: b) The process is not capable

If Cpk = 1.5, it implies that:
a) The process is centered and capable
b) The process is capable but not centered
c) The process is unstable
d) None of the above
Answer: b) The process is capable but not centered

What is the Cp for a process with a specification range of 80 to 120 and a standard deviation of 5?
a) 2
b) 1.33
c) 1.5
d) 4
Answer: a) 2

29. Practical Applications

In manufacturing, SPC helps:
a) Detect machine wear before defects occur
b) Reduce employee training time
c) Eliminate the need for quality inspections
d) None of the above
Answer: a) Detect machine wear before defects occur

In software development, SPC can monitor:
a) Bugs reported per release
b) Development time for each feature
c) Server uptime percentage
d) All of the above
Answer: d) All of the above

In the food industry, SPC is used to:
a) Monitor packaging defects
b) Ensure consistent ingredient quality
c) Track temperature control during production
d) All of the above
Answer: d) All of the above

30. Statistical Quality Control

The primary goal of statistical quality control (SQC) is to:
a) Reduce production costs
b) Eliminate all defects
c) Monitor and control product quality
d) Improve employee efficiency
Answer: c) Monitor and control product quality

In SQC, a Pareto chart is used to:
a) Measure process capability
b) Identify the most significant defects or issues
c) Determine control chart limits
d) Calculate sample size
Answer: b) Identify the most significant defects or issues

The term "quality at the source" in SPC means:
a) Inspecting quality at the end of the production line
b) Building quality into the process to prevent defects
c) Using SPC charts at the final inspection stage
d) Delegating quality checks to suppliers
Answer: b) Building quality into the process to prevent defects

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