Chapter 3: Statistical Quality Control (True/False)
26. A control chart is in control when the plot of the sample points exhibits a pattern.
False, LO: 5, Bloom: K, Difficulty: Moderate, AACSB:
33. Tolerances reflect the amount of common cause variation allowed in a process.
False, LO: 7, Bloom: K, Difficulty: Moderate, AACSB:
34. For a given process, the process capability ratio is not related to its specification limits.
False, LO: 7, Bloom: K, Difficulty: Moderate, AACSB:
7. Common cause (random) variation provides evidence that the process is not in control.
False, LO: 1, Bloom: K, Difficulty: Easy, AACSB:
32. Tolerances or specification limits are allowable variation prescribed in a product design.
True, LO: 7, Bloom: K, Difficulty: Moderate, AACSB:
6. A process that is determined to be in control contains no variation.
False, LO: 1, Bloom: K, Difficulty: Easy, AACSB:
, 2. Statistical process control is based on a philosophy of inspection as opposed to prevention.
False, LO: 1, Bloom: K, Difficulty: Moderate, AACSB:
5. Control limits are based on the special cause (nonrandom) variation inherent in a process.
False, LO: 1, Bloom: K, Difficulty: Moderate, AACSB:
10. When a control chart detects no special cause (nonrandom) variation in a process, the upper and lower control limits are the same value.
False, LO: 2, Bloom: K, Difficulty: Hard, AACSB:
12. A variable measure classifies while an attribute measure quantifies.
False, LO: 2, Bloom: K, Difficulty: Moderate, AACSB:
16. The formula used to determine the upper and lower control limits are based on product specification limits.
False, LO: 4, Bloom: K, Difficulty: Easy, AACSB:
1. Statistical process control involves monitoring and controlling a process to prevent poor quality.
True, LO: 1, Bloom: K, Difficulty: Easy, AACSB:
3. One goal of statistical process control is to prevent a process from producing items that have to be scrapped or reworked.
True, LO: 1, Bloom: K, Difficulty: Easy, AACSB:
4. Two types of variation associated with the output of a process are common cause (random) and special cause (nonrandom).
True, LO: 1, Bloom: K, Difficulty: Easy, AACSB:
8. After special cause variation is detected, the focus changes to identifying the root cause of the variation and eliminating it.
True, LO: 1, Bloom: K, Difficulty: Hard, AACSB:
11. It is sometimes not necessary to determine new control limits after special cause (nonrandom) variation has been identified if the source has been eliminated without changing the process.
True, LO: 2, Bloom: K, Difficulty: Hard, AACSB:
9. Process control is achieved by taking periodic samples from a process and plotting the sample points on a chart to determine if the process is within control limits.
True, LO: 2, Bloom: K, Difficulty: Moderate, AACSB:
13. With a c-chart, the sample size is small and may contain only one item.
True, LO: 3, Bloom: K, Difficulty: Easy, AACSB:
14. A p-chart is used to monitor the proportion defective in the output of a process.
True, LO: 3, Bloom: K, Difficulty: Easy, AACSB:
17. Variable control charts are used to monitor measurable characteristics of a process's outputs rather than descriptive characteristics.
True, LO: 4, Bloom: K, Difficulty: Easy, AACSB:
21. The range is the difference between the smallest and largest values in a sample.
True, LO: 4, Bloom: K, Difficulty: Easy, AACSB:
20. Construction and use of an -chart is based on an assumption that the sample points are normally distributed around the centerline.
True, LO: 4, Bloom: K, Difficulty: Hard, AACSB:
18. An x-bar and R-chart constructed to monitor and control a process use the same raw data.
True, LO: 4, Bloom: K, Difficulty: Moderate, AACSB:
19. Variable control charts are used for quantitative measures such as weight or time.
True, LO: 4, Bloom: K, Difficulty: Moderate, AACSB:
22. The range measures the variation within samples versus the variation between samples.
True, LO: 4, Bloom: K, Difficulty: Moderate, AACSB:
23. It is possible to have low variation within samples while at the same time having high variation between sample means.
True, LO: 4, Bloom: K, Difficulty: Moderate, AACSB:
30. Control charts visually show when a process is not within statistical control limits.
True, LO: 5, Bloom: K, Difficulty: Easy, AACSB:
24. One advantage of using a pattern test is that special cause variations may be identified before any points are plotted outside the control limits.
True, LO: 5, Bloom: K, Difficulty: Moderate, AACSB:
25. A pattern test can identify an out-of-control process even if all sample points are within control limits.
True, LO: 5, Bloom: K, Difficulty: Moderate, AACSB:
27. If the points plotted on a control chart display a pattern, it is called a run.
True, LO: 5, Bloom: K, Difficulty: Moderate, AACSB:
28. When constructing a control chart for the first time, all points should be within the control limits indicating the process is in control.
True, LO: 5, Bloom: K, Difficulty: Moderate, AACSB:
29. Process control charts are often used at a critical point after which it is difficult to correct or rework the process output.
True, LO: 5, Bloom: K, Difficulty: Moderate, AACSB:
31. The popularity of Excel and other data analysis software has been a major factor in the increased use of statistical process control.
True, LO: 6, Bloom: K, Difficulty: Moderate, AACSB:
36. All processes contain a certain amount of variation in their output.
True, LO: 7, Bloom: K, Difficulty: Easy, AACSB:
37. A sequence of sample points that display a pattern is known as a run.
True, LO: 7, Bloom: K, Difficulty: Easy, AACSB:
35. A process capability ratio greater than one shows that a process is capable of producing output within its specification limits.
True, LO: 7, Bloom: K, Difficulty: Moderate, AACSB:
38. Statistical process control can prevent poor quality before it occurs if a pattern is evident in the plotted points.
True, LO: 7, Bloom: K, Difficulty: Moderate, AACSB:
39. The process capability index indicates how much a process mean differs from the target specification value.
True, LO: 7, Bloom: K, Difficulty: Moderate, AACSB:
15. Attribute control charts are used to monitor descriptive characteristics of the output of a process rather than measurable characteristics.
True, LO:3, Bloom: K, Difficulty: Easy, AACSB:
