# Statistical Quality Control Questions and Answers – Attribute Control Charts – Choice between Attributes and Variable Control Charts – 2

This set of Statistical Quality Control Multiple Choice Questions & Answers (MCQs) focuses on “Attribute Control Charts – Choice between Attributes and Variable Control Charts – 2”.

1. Which of these is a condition where attributes control charts should be used?
a) New product manufacturing from existing process
b) Troubleshooting a out-of-control process
c) When it is necessary to reduce process fallout
d) Change in product specification is required

Explanation: When it is necessary to reduce process fallout, and when the operators control the assignable causes, Attributes control charts are chosen over the Variables control chart.

2. When the process is a complex assembly operation, and the product quality can only be judged in terms of occurrence of nonconformities, the ______ are more helpful.
a) Only x Charts
b) R-charts
c) s-charts
d) p-charts

Explanation: When the process is a complex assembly operation and the product quality is assessed only on basis of occurrence of defects, the p-charts are more helpful.

3. When process needs to be controlled but the measurement data cannot be obtained, the control charts to be formed are _____________
a) p-charts
b) Only x Charts
c) s-charts
d) R-charts

Explanation: When process needs to be controlled but the measurement data can’t be acquired, the attributes charts are the better choice than the variables control chart.

4. When there are very tight specifications, overlapping assembly tolerances problems, which of the control charts are used?
a) Attributes control charts
b) Variables control charts
c) Both, attributes control charts and the variables control charts can be used
d) Neither one of attributes or variables control charts can be used

Explanation: Variable control charts are more favored when there are very tight specifications, overlapping assembly tolerances problems. This is because variables control charts deal better with specifications of quality characteristics than the attributes control chart.

5. When destructive testing is required, which type of control should be used?
a) p-chart
b) c-chart
c) x And R charts
d) u-charts

Explanation: When destructive testing is required or any other expensive testing procedure is needed, variable control charts are more suitable than the attributes control chart.

6. When attributes charts are used when _______
a) Destructive testing is required
b) Process must be continuously stabilized and monitored for its capability
c) Historical summary of process performance is needed
d) Existing process but in chronic trouble

Explanation: When historical summary of process performance is needed for the variables control charts, attributes control charts are used to develop the summary data.

7. When there is a need to reduce acceptance-sampling or other downstream testing to a minimum when the process can be operated in-control, which type of control charts should be preferred?
a) Attributes control chart
b) Variable control chart
c) Both can be used
d) None of the both types can be used

Explanation: When the acceptance sampling is to be reduced to minimum, the variables charts reveal better results and efficiency than the attributes control chart.

8. Which of these does not require SPC implementation?
a) When Specifications change without notice
b) When customer demands both control and capability
c) When process is stable
d) When the process is estimated to reduce its capability in near future

Explanation: SPC implementation is required when the specifications change without notice, and customer demands both control and capability, and when the process is predicted to reduce its capability in near future.

9. When it is inconvenient to obtain more than one measurement per sample output of any process, which of these is the best choice?
a) x bar and R charts
b) x bar and s charts
c) c-charts
d) Control charts for individuals

Explanation: The times when, it is inconvenient or impossible to obtain more than one measurement per sample, or repeat measurements will only be affected by lab or analysis error, the control charts for individuals are the best choice, e.g. Often in chemical processes.

10. Which of these should be carried out if the process is in-control and capable?
a) SPC only
b) Experimental design
c) Change process
d) Investigate specifications

Explanation: If the process currently studied is in control and also capable, the control and capability of the process are maintained as it is, by using the statistical process control only.

11. Computer should not be used with SPC.
a) True
b) False

Explanation: Some SPC consultants don’t recommend the use of computers with SPC. But now it is necessary to use computers with SPC as manual control charting cannot be transmitted to whole over company branches. Company-wide database can be updated using computers only.

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