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| 1 | |
What does the phrase "in control" mean with respect to processes? |
| | A) | An in-control process is one in which the proportion of output that is defective falls within the agreed-upon range |
| | B) | An in-control process is one in which the process width (i.e., 6σ) is substantially wider than the specification width (i.e., the upper specification limit minus the lower specification limit) |
| | C) | An in-control process is statistically stable; it is free of assignable or non-random variation |
| | D) | An in-control process is statistically stable; it is free of unassignable or random variation |
| | E) | None of these is correct |
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| 2 | |
The purpose of control charts is to: |
| | A) | estimate the proportion of output that is acceptable |
| | B) | weed out defective items |
| | C) | determine if the output is within tolerances/specifications |
| | D) | distinguish between random variation and non-random variation in the process |
| | E) | none of these |
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| 3 | |
The most important parameter in statistical quality control is the: |
| | A) | mean |
| | B) | range |
| | C) | variance |
| | D) | proportion |
| | E) | bar chart |
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| 4 | |
The statistician who invented the control chart for use in industrial quality control was: |
| | A) | Deming |
| | B) | Taguchi |
| | C) | Pareto |
| | D) | Shewhart |
| | E) | none of the above |
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| 5 | |
The chart which aggregates poor quality outcomes to show management which are the most important problems is the: |
| | A) | s chart |
| | B) | Pareto chart |
| | C) | R chart |
| | D) | x-bar chart |
| | E) | Taguchi chart |
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| 6 | |
Control chart limits for a measured characteristic have been calculated as follows (assume a sample size of n = 5): UCLx-bar = 218.45 UCLR = 12.90
LCLx-bar = 208.45 LCLR = 0
Suppose a sample has been drawn consisting of the following observations: 222.8 219.8 213.7 209.3 219.6
If we base our conclusions solely on the information in this sample, what should be concluded about this process, and why? |
| | A) | This process is out of control; the sample range exceeds the control limits for R |
| | B) | This process is out of control; the sample average exceeds the control limits for x-bar |
| | C) | This process is out of control; both the sample average and the sample range exceed their control limits |
| | D) | This process is out of control; several observations fall outside the control limits for x-bar |
| | E) | This process is in control; both the sample average and the sample range are within their respective control limits |
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| 7 | |
In statistical process control, p-charts are used to signal assignable variation that is affecting the ___________: |
| | A) | sample size |
| | B) | number of defects in a typical unit of output |
| | C) | proportion of defective units being produced |
| | D) | useful life period of units produced |
| | E) | proportion of variability that can be attributed to random factors |
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| 8 | |
The chart which involves the number of defects per item, is called the _________ chart. |
| | A) | x-bar |
| | B) | x |
| | C) | R |
| | D) | s |
| | E) | c |
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| 9 | |
In the c chart, c is estimated by c-bar which is the: |
| | A) | average range of each group |
| | B) | average number of defects per item |
| | C) | average number of defective items in the entire population |
| | D) | standard deviation of the number of defectives |
| | E) | proportion of defects in each group |
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| 10 | |
The lower control limit for p charts is: |
| | A) | sometimes zero |
| | B) | always zero |
| | C) | never zero |
| | D) | p-bar - [(p-bar)(1 - (p-bar))] |
| | E) | none of the above |
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| 11 | |
Suppose we have calculated upper and lower control limits for the sample proportion as, respectively, 0.12 and 0.08. In our latest sample of 200 observations, 26 were defective. Because we calculated our limits as representing +/− 3σ of the sample proportion, we are _______________ certain the process is _______________. |
| | A) | 99.74%; in control |
| | B) | 99.74%; out of control |
| | C) | 0.26%; out of control |
| | D) | 0.26%; capable |
| | E) | 99.74%; capable |
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| 12 | |
When a process is in control, the standard deviation in samples of size n = 7 averages 3.5. What would upper and lower control limits for the control charts for s be? |
| | A) | UCLs = 5.687; LCLs = 4.013 |
| | B) | UCLs = 6.875; LCLs = 0 |
| | C) | UCLs = 6.587; LCLs = 0.413 |
| | D) | UCLs = 13.174; LCLs = 0.826 |
| | E) | UCLs = 13.714; LCLs = 0.286 |
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