Statistical Quality Control Questions and Answers – Control Charting Techniques – Statistical Process Control for Short Production Runs – 5

«
»

This set of Statistical Quality Control Multiple Choice Questions & Answers (MCQs) focuses on “Control Charting Techniques – Statistical Process Control for Short Production Runs – 5”.

1. When the type I error is specified, which of these is correct expression for the UCL of the modified control charts?
a) \(UCL=USL-\left(Z_δ+\frac{Z_α}{\sqrt{n}}\right) \sigma \)
b) \(UCL=USL-\left(Z_δ-\frac{Z_α}{\sqrt{n}}\right) \sigma \)
c) \(UCL=USL+\left(Z_δ+\frac{Z_α}{\sqrt{n}}\right) \sigma \)
d) \(UCL=USL+\left(Z_δ-\frac{Z_α}{\sqrt{n}}\right) \sigma \)
View Answer

Answer: b
Explanation: The modified control charts are the alternatives of ordinary Shewhart control charts, when the process capability is high. These have UCL as,
\(UCL=USL-\left(Z_δ-\frac{Z_α}{\sqrt{n}}\right) \sigma \)
advertisement

2. Which of these is a correct expression for the UCL of the modified control charts when the type I error is not specified?
a) \(UCL=USL+\left(Z_δ+\frac{3}{\sqrt{n}}\right) \sigma \)
b) \(UCL=USL+\left(Z_δ-\frac{3}{\sqrt{n}}\right) \sigma \)
c) \(UCL=USL-\left(Z_δ-\frac{3}{\sqrt{n}}\right) \sigma \)
d) \(UCL=USL-\left(Z_δ+\frac{3}{\sqrt{n}}\right) \sigma \)
View Answer

Answer: c
Explanation: The UCL of the modified control charts can be done by both, specifying the type I error or by not specifying the type I error. When the type I error is not specified, the UCL is,
\(UCL=USL-\left(Z_δ-\frac{3}{\sqrt{n}}\right) \sigma \)

3. When the type I error is not specified, the value of LCL of the modified control charts is ____________
a) \(LCL=LSL+\left(Z_δ-\frac{3}{\sqrt{n}}\right) \sigma \)
b) \(LCL=LSL-\left(Z_δ+\frac{3}{\sqrt{n}}\right) \sigma \)
c) \(LCL=LSL-\left(Z_δ-\frac{3}{\sqrt{n}}\right) \sigma \)
d) \(LCL=LSL+\left(Z_δ+\frac{3}{\sqrt{n}}\right) \sigma \)
View Answer

Answer: a
Explanation: The LCL of the modified control chart also uses the type I error. If the type I error is not to be specified. Its value is written by the expression,
\(LCL=LSL+\left(Z_δ-\frac{3}{\sqrt{n}}\right) \sigma \)

4. ____________ sigma limits are recommended for modified control charts.
a) 4
b) 2
c) 3
d) 6
View Answer

Answer: b
Explanation: The modified control charts are effective when the spread of process is quite less than the limits used. So 2-sigma limits are recommended for the modified control charts.

5. Which of the hypothesis can be tested using the modified control charts?
a) μL ≤ μ ≤ μU
b) μL ≤ μ
c) μ ≤ μU
d) μL = μ = μU
View Answer

Answer: a
Explanation: The modified control charts allow the mean shift between two particular mean values. This means that the hypothesis μL ≤ μ ≤ μU can be tested using the modified control charts.
advertisement

6. To design a modified control chart, we must have a good estimate of _________ available.
a) μ
b) σ
c) μ2
d) process variance
View Answer

Answer: b
Explanation: The modified control chart limits are totally based upon the estimate of the process standard deviation. So, to design a modified control chart, we must have a good estimate of σ available.

7. If process variability shifts, the modified control charts are ____________
a) Not appropriate
b) Totally appropriate
c) Good to use
d) Perfect for the mapping the shifts
View Answer

Answer: a
Explanation: A modified control chart needs a good estimate of the process standard deviation. As the process standard deviation is depended upon the process variability, the modified control charts are not appropriate to use.

8. If there is a chance of shifting of the process variability, which chart may be used with the modified control chart?
a) c-chart
b) p-chart
c) R-chart
d) x̅ -chart
View Answer

Answer: c
Explanation: As the process variability shifts can be monitored using a Shewhart R chart or an s-chart, if there is a chance of shifting of the process variability, they can be used in conjunction with modified control charts.

9. From which chart the initial estimate of the process variability is determined?
a) R-chart
b) c-chart
c) p-chart
d) Cusum charts
View Answer

Answer: a
Explanation: As R charts and s-charts are good ways to estimate the process standard deviation, hence the process variability too, they are used to determine the initial estimate of the process variability.
advertisement

10. When the type I error is specified, the LCL of the modified control chart is ___________
a) \(LCL=LSL-\left(Z_δ-\frac{Z}{\sqrt{n}}\right)\)
b) \(LCL=LSL-\left(Z_δ+\frac{Z}{\sqrt{n}}\right)\)
c) \(LCL=LSL+\left(Z_δ+\frac{Z}{\sqrt{n}}\right)\)
d) \(LCL=LSL+\left(Z_δ-\frac{Z}{\sqrt{n}}\right)\)
View Answer

Answer: d
Explanation: As the type I error is not specified, the value of the 100(1-δ) percentage point of the normal distribution Zδ is used. The LCL is,
\(LCL=LSL+\left(Z_δ-\frac{Z}{\sqrt{n}}\right)\)

11. The approach of using a x chart to monitor the fraction of nonconforming units or the fraction of the units exceeding the specifications, is called the ___________
a) Shewhart control charts
b) Cusum charts
c) EWMA charts
d) Acceptance control charts
View Answer

Answer: d
Explanation: There is an approach to using an x chart to monitor the fraction of nonconforming or defective units, or the fraction of the units exceeding the specifications, which is called Acceptance control chart.

12. Who was the first person to develop the acceptance control charts?
a) Astern
b) Roy
c) Freund
d) Crowder
View Answer

Answer: c
Explanation: The first person, to develop a method to use the x chart to monitor the fraction of defective units, was Freund (1957). He first developed the technique of the acceptance control charts.

13. A modified control charts limit expression does not contain ___________
a) δ
b) σ
c) μ
d) α
View Answer

Answer: c
Explanation: The modified control charts was based on a specific sample size n, a process nonconforming δ, and type I error probability α. It does not depend on μ.
advertisement

14. The p-chart is the only chart to monitor the fraction of nonconforming units.
a) True
b) False
View Answer

Answer: b
Explanation: The acceptance charts is based on the approach of using the x̅ chart to monitor the fraction of nonconforming units. So p-chart is not the only chart to monitor the fraction nonconforming units.

15. If the process mean increases very much, the modified control charts are not appropriate.
a) True
b) False
View Answer

Answer: a
Explanation: As modified control charts are based on the assumption that the process has a very high capability, and the mean does not shift very significantly, if the mean shifts very much, the modified control chart becomes inappropriate.

Sanfoundry Global Education & Learning Series – Statistical Quality Control.

To practice all areas of Statistical Quality Control, here is complete set of 1000+ Multiple Choice Questions and Answers.

Participate in the Sanfoundry Certification contest to get free Certificate of Merit. Join our social networks below and stay updated with latest contests, videos, internships and jobs!

advertisement
advertisement
advertisement
Manish Bhojasia, a technology veteran with 20+ years @ Cisco & Wipro, is Founder and CTO at Sanfoundry. He is Linux Kernel Developer & SAN Architect and is passionate about competency developments in these areas. He lives in Bangalore and delivers focused training sessions to IT professionals in Linux Kernel, Linux Debugging, Linux Device Drivers, Linux Networking, Linux Storage, Advanced C Programming, SAN Storage Technologies, SCSI Internals & Storage Protocols such as iSCSI & Fiber Channel. Stay connected with him @ LinkedIn