Management And Accounting Web

# Statistical Process Control MC Questions

Provided by James R. Martin, Ph.D., CMA
Professor Emeritus, University of South Florida

Note: Questions 1-17 are from MAAW's Textbook Chapter 3 Extra MC questions.

1. Using the terminology of statistical control, the variation within a stable system

a. is random variation.
b. results from common causes.
c. is predictable within a range.
d. a and b.
e. all of the above.

2. Using the terminology of statistical control, the variation outside the control limits on an X-bar or range chart

a. is viewed as uncontrollable.
b. is assumed to have been caused by special or assignable causes.
c. indicates that the system is probably out of control.
d. b and c.
e. all of the above.

3. One type of error a manager can make is to blame a worker for an undesirable variation that is caused by the system. Refer to this as a type I error. Another type of error a manager can make is to blame the system when a worker caused the undesirable variation. Refer to this as a type II error. If a company changed the basis for the upper and lower limits on a control chart from three standard deviations to two standard deviations

a. the number of type I errors would increase.
b. the number of type II errors would increase.
c. the number of both types of errors would increase.
d. the number of both types of errors would decrease.
e. there is no basis for choosing an answer.

4. One type of error a manager can make is to blame a worker for an undesirable variation that is caused by the system. Refer to this as a type I error. Another type of error a manager can make is to blame the system when a worker caused the undesirable variation. Refer to this as a type II error. If a company changed the basis for the upper and lower limits on a control chart from two standard deviations to three standard deviations

a. the number of type I errors would increase.
b. the number of type II errors would increase.
c. the number of both types of errors would increase.
d. the number of both types of errors would decrease.
e. there is no basis for choosing an answer.

5. Using the terminology associated with statistical process control (SPC), the variation within a stable system is

a. predictable within a range of values.
b. controllable.
c. in control.
d. a and b.
e. a and c.

6. Using the terminology associated with SPC, the variations resulting from common causes are attributed to

a. an out of control situation which should be investigated.
b. an in control situation which should not be investigated.
c. an out of control situation which should not be investigated.
d. an in control situation which should be investigated.
e. none of the above.

7. Using the terminology of statistical process control, a variation caused by the system is

a. common cause variation.
b. assignable cause variation.
c. special cause variation.
d. a and b.
e. b. and c.

8. Using the terminology of statistical process control, a variation that indicates that the system may be out of control is

a. common cause variation.
b. assignable cause variation.
c. special cause variation.
d. a and b.
e. b. and c.

9. Using the terminology of statistical process control (SPC), Type I errors are where common cause variation is treated as assignable cause variation. Type II errors are where assignable cause variation is treated as common cause variation. Which of the situations below would minimize type II errors?

a. Use SPC charts where the limits are based on 3 standard deviations.
b. Use SPC charts where the limits are based on 2 standard deviations.
c. Use SPC charts where the limits are based on 1 standard deviation.
d. Use budget comparisons against actual results without using the concept of SPC.

10. Which of the situations below would minimize type I errors?

a. Use SPC charts where the limits are based on 3 standard deviations.
b. Use SPC charts where the limits are based on 2 standard deviations.
c. Use SPC charts where the limits are based on 1 standard deviation.
d. Use budget comparisons against actual results without using the concept of SPC.

11. Using the terminology of statistical process control (SPC), a stable system is

a. efficient.
b. predictable.
c. in control.
d. b and c.
e. All of the above.

12. In general, finding and correcting an assignable cause variation

a. represents an improvement in the system.
b. returns the system from an unstable to a stable state.
c. represents a type I error.
d. a and b.
e. b. and c.

13. Conceptually, control requires

a. standards.
b. a stable system.
c. statistically established limits.
d. a. and b.
e. b. and c.

14. Statistically, an improvement in a system is defined as

a. an improvement in the mean outcome.
b. a decrease in the system variability.
c. a correction of an assignable cause.
d. a and b.
e. all of the above.

15. When using the SPC methodology, a system is said to be stable when

a. the system is efficient.
b. the mean and range of variation caused by the system are controllable.
c. the mean and range of variation caused by the system are predictable.
d. the performance of the system is improving.
e. none of these.

16. When using a statistical control chart (SPC), a point outside the control limits is attributed to

a. common or random causes.
b. assignable or special causes.
c. a problem caused by the system.
d. a and c.
e. b and c.

17. A predictable range of variation in the output of a particular worker occurs on a routine basis. This variation represents

a. common cause variation and is uncontrollable.
b. common cause variation and is controllable.
c. assignable cause variation and is uncontrollable.
d. assignable cause variation and is controllable.
e. none of these.

18. Joiner and Gaudard use the term structural variation in discussing Demingâ€™s theory. This is

a. common cause variation and uncontrollable.
b. common cause variation and controllable.
c. assignable cause variation and uncontrollable.
d. assignable cause variation and controllable.
e. none of these.

19. Deming used the red bead experiment to teach that

a. most of the variation in a system is assignable cause variation.
b. most of the variation in a system is common cause variation.
c. the variation caused by the system is equally distributed across a group of workers.
d. a. and c.
e. b. and c.

20. The red bead experiment was designed to show that

a. workers tend to control their own performance.
b. special or assignable causes account for most of the variation in performance.
c. common or random causes account for most of the variation in performance.
d. a balanced plant is not obtainable.
e. a and c.