Page 443 - Six Sigma Demystified

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53. A process shows statistical control using an individual-X chart. Assuming that the
implementation cost of a different chart is negligible but the cost of sampling is
significant, the most economical method for increasing the sensitivity of the chart
to small process shifts is to
A. increase the subgroup size.
b. use an EWMA or CuSum chart.
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c. use the X range chart.
d. All the above are true.

54. When a process is extremely nonnormal,
A. an individual-X chart with control limits defined at plus and minus 3σ from the
process mean may predict control limits that don’t match the process.
b. an EWMA or moving-average chart may be useful because the plotted points
assume normality.
c. you should understand why the process is so distributed.
d. All the above are true.

55. Gauge R&R studies are best done using
A. calibration standards.
b. actual samples from the process.
c. vendor samples.
d. only the best operators.

56. Gauge R&R studies may be used to
A. understand and reduce common causes of variation in a process.
b. ensure that process personnel can take process measurements with minimal error.
c. compare the performance of new test equipment.
d. All the above are true.
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57. When using a X range chart for evaluating gauge repeatability,
A. the range chart indicates the variation between operators.
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b. the X chart should be out of control.
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c. the X chart is scaled using the process variation.
d. All the above are true.
58. A criterion for acceptance of gauge R&R is that
A. the calculated R&R should be less than 10 percent of process variation.
b. the calculated R&R should be less than 10 percent of process tolerances.
c. the calculated discrimination should be more than 8 or 10.
d. All the above are true.

59. Histograms
A. give us a graphic view of process location and variation.
b. provide of quick means of checking process control.
c. detect subtle trends in the process.
d. All the above are true.