MGMT 425 Ch.8 MC

Which of the following statements regarding a major advantage of np-charts is true? a. They can be used for variable sample sizes. b. They are more accurate than p-charts. c. They are easier to understand for production personnel than p-charts. d. The control limits are based on binomial distribution.

They are easier to understand for production personnel than p-charts.

Which of the following is a likely cause of the control chart pattern known as a trend? a. Aging of equipment b. Maintenance schedules c. New process operator d. Sudden power surge

a. Aging of equipment

Which of the following is NOT an indication of an out-of-control process? a. Five consecutive points fall on one side of the center line. b. Four of five consecutive points fall within the outer two-thirds region between the center line and one of the control limits. c. Two of three consecutive points fall in the outer one-third region between the center line and one of the control limits. d. A single point falls above the upper control limit.

a. Five consecutive points fall on one side of the center line.

In determining whether a process is in statistical control, the _____ should be analyzed first. a. R-chart b. upper and lower control limits c. -chart d. center line

a. R-chart

If the lower limit for a p-chart computes to a number less than zero, this indicates that a. the lower limit should be set at zero. b. the process is out of control. c. an attribute measure is incorrectly used. d. a calculation error has been made.

a. the lower limit should be set at zero.

The _____ is used to monitor the centering of the process. a. xbar-chart b. R-chart c. p-chart d. np-chart

a. xbar-chart

Defects per million opportunities (dpmo) = a. (Number of defects discovered)/Opportunities for error × 100,000. b. (Number of defects discovered)/Opportunities for error × 1,000,000. c. (Opportunities for error × Number of defects discovered)/1,000,000. d. (Opportunities for error/Number of defects discovered) × 10,000,000.

b. (Number of defects discovered)/Opportunities for error × 1,000,000.

_____ is measured as the amount of error in a measurement in proportion to the total size of the measurement. a. Precision b. Accuracy c. Systematic bias d. Capability

b. Accuracy

In pre-control, which of the following zones covers the nominal specifications of a process? a. Gray zone b. Green zone c. Red zone d. Yellow zone

b. Green zone

A company wishes to monitor the variation in the length of time it takes to process and send a bill to a customer. Seven bills will be randomly selected each day for a 60-day period and the length of time it takes to process and send the bill to a customer will be recorded for each bill. The appropriate control chart is a(n) a. -chart. b. R-chart. c. p-chart. d. u-chart.

b. R-chart.

Which of the following is NOT one of the basic applications of a control chart? a. To establish a state of statistical control. b. To calculate the average range. c. To monitor a process to identify special causes of variation. d. To determine process capability.

b. To calculate the average range.

Short, repeated patterns in a control chart, with alternating high peaks and low valleys, are known as a. trends. b. cycles. c. shifts. d. runs.

b. cycles.

The output of a process is stable and normally distributed. If the process mean equals 23.5, the percentage of output expected to be less than or equal to the mean a. is less than 25 percent. b. is 50 percent. c. is greater than 75 percent. d. cannot be determined without knowing the standard deviation value.

b. is 50 percent.

Process capability calculations make little sense if the process a. data were taken over time. b. is not in statistical control. c. variations are due to common causes. d. is not initiated.

b. is not in statistical control.

All else being constant, if the sample size in a p-chart increases from 100 to 120, the upper and lower control limits will a. move farther apart. b. move closer together. c. not be affected. d. both shift upward.

b. move closer together.

For variables data, the sample means are assumed to be a. exponentially distributed. b. normally distributed. c. Poisson distributed. d. binomially distributed.

b. normally distributed.

A better alternative to using the R-chart to monitor variation is the a. np-chart. b. s-chart. c. c-chart. d. p-chart.

b. s-chart.

A process is said to be out of control when a. common causes are present. b. special causes are present. c. the process is not capable of meeting specifications. d. the upper and lower control limits cannot be computed.

b. special causes are present.

The s-chart is recommended when a. the control chart calculations need to be performed by hand. b. tight control of variability in the process is required. c. the -chart is not associated with an R-chart. d. the sample size for each sample needs to be reduced.

b. tight control of variability in the process is required.

Which of the following charts is used to monitor the average number of nonconformances per unit when sample sizes vary? a. xbar -chart b. u-chart c. p-chart d. c-chart

b. u-chart

Which of the following statements regarding an x-chart is true? a. Individual data require averaging before being plotted on it. b. It is less sensitive to many conditions that can be detected by the xbar-chart and R-chart. c. Specification limits cannot be drawn on the chart for direct comparison with the control limits. d. The assumption of normality of observations is less critical than for the -chart and R-chart.

b. It is less sensitive to many conditions that can be detected by the -chart and R-chart.

_____ is a study of variation in a measurement system using statistical analysis. a. A metrology study b. An SPC study c. A repeatability and reproducibility (R&R) study d. A calibration study

c. A repeatability and reproducibility (R&R) study

A c-chart is based on the _____ probability distribution. a. normal b. binomial c. Poisson d. exponential

c. Poisson

Compared to variable measurement, attributes measurement requires _____ to obtain the same amount of statistical information about the quality of the product. a. a more distributed population b. more nonconformances c. a much larger sample size d. a smaller sample size

c. a much larger sample size

A(n) _____ measurement characterizes the presence or absence of nonconformances in a unit of work. a. variable b. indicator c. attribute d. error

c. attribute

Collecting _____ data is usually easier than collecting _____ data because the assessment can usually be done more quickly by a simple inspection or count. a. variable; attribute b. conformances; nonconformances c. attribute; variable d. simple; complex

c. attribute; variable

Variable data are a. discrete. b. not measurable. c. continuous. d. nonrandom.

c. continuous.

Statistical process control relies on a. process capability studies. b. dashboards. c. control charts. d. metrology.

c. control charts.

In service applications, the term _____ is generally used to describe a nonconformance. a. cycle b. unit c. error d. trend

c. error

If the variation in the process is due to common causes alone, the process is said to be a. out of control. b. in pre-control. c. in statistical control. d. out of capability.

c. in statistical control.

The x-chart is used for a. averages of variables data. b. individual attributes data. c. individual variables data. d. averages of attributes data.

c. individual variables data.

The sample size for an x-chart a. should be between 25 and 30. b. is larger than that for an -chart. c. is equal to one. d. should be greater than one.

c. is equal to one.

If a process is neither capable nor in control, the appropriate first step is to a. remove common causes of variation. b. redesign the equipment. c. remove special causes of variation. d. determine the process capability index.

c. remove special causes of variation.

Control limits are often confused with a. pre-control lines. b. center lines. c. specification limits. d. three sigma limits.

c. specification limits.

If the process mean and variance do not change over time, the process is a. in statistical control. b. normally distributed. c. stable. d. capable.

c. stable.

Because of high test costs, a sample of single wastewater sludge is tested daily for dissolved oxygen content. The appropriate control chart(s) would be a. xbar-chart and R-chart. b. u-chart. c. x-chart and moving range chart. d. x-chart and R-chart.

c. x-chart and moving range chart.

Which of the following pairs of charts are used together? a. xbar-chart and p-chart b. R-chart and p-chart c. R-chart and s-chart d. -chart and R-chart

d. -chart and R-chart

A(n) _____ monitors the fraction of nonconforming units. a. c-chart b. u-chart c. np-chart d. p-chart

d. p-chart

A _____ is the result of some cause that gradually affects the measurement and causes the points on a control chart to gradually move up or down from the center line. a. defect b. process shift c. cycle d. trend

d. trend

For statistical process control, a good sampling method should always a. use samples of random measurements over a long period of time. b. minimize sampling cost. c. maximize sample size. d. use rational subgroups.

d. use rational subgroups.