Statistics Multiple Choice Questions

Question: Statistical process control relies on _____.

A Capability models

B Variance analyses

C Control charts

D Conformance reports

Question: Twenty samples of size 6 were collected for a variable measurement. Determine the upper control limit (UCL) and lower control limit (LCL) for an R-chart if the sum of the sample ranges equals 88.0.

A UCL = 8.8176, LCL = 0.0000

B UCL = 9.3016, LCL = 0.3344

C UCL = 13.2000, LCL = 0.0000

D UCL = 29.3921, LCL = 0.0000

Question: x-charts are used for

A Averages of variables data

B Individual attribute data

C Individual variables data

D Averages of attributes data

Question: In determining whether a process is in statistical control, the _____ is/are generally analyzed first.

A R-chart

B Control limits

C Average range

D Nonconformance

Question: In pre-control, which zone covers the nominal dimension?

A Gray zone

B Yellow zone

C Red zone

D Green zone

Question: 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

Question: A machined part has a lower tolerance limit of 3.5 inches and an upper tolerance limit of 3.9 inches. The range for the pre-control green zone is

A 3.5 to 3.9 inches

B 3.7 inches to 3.9 inches

C Less than 3.5 inches

D 3.6 inches to 3.8 inches

Question: If the process mean and variance do not change over time, the process is considered to be

A In control

B Symmetric

C Stable

D Capable

Question: Each day, a manufacturing company producing circuit boards will randomly sample 60 circuit boards and then determine and plot the number of defects contained in each of these boards. The appropriate control chart is a

A  -chart

B p-chart

C np-chart

D c-chart

Question: Control limits relate to _____, while specification limits relate to individual measurements.

A Values within the upper and lower control limits

B Total values in the range

C Median values

D Averages of samples

Question: A precision parts manufacturer produces bolts for use in military aircraft. The specifications for bolt length are 37.50 ± 0.25 cm. The company has established an  -chart and an R-chart using samples of size five. The centerlines for the  -chart and R-chart are set at 37.65 cm and 1.03 cm, respectively. What is the value of Cp for this process?

A 0.188

B 1.333

C 0.301

D 0.166

Question: The control chart most appropriate for plotting the daily percentage of students that wait longer than five minutes in line at the undergraduate admissions office is a(n)

A p-chart

B np-chart

C x-chart

D  -chart

Question: The _____ is used to monitor the centering of the process.

A  -chart

B R-chart

C p-chart

D np-chart

Question: If the traditional 3-sigma limits on a control chart are replaced by 2-sigma limits, which of the following is TRUE?

A Type I errors decrease

B Type I errors increase

C Type II errors increase

D The center line moves downward

Question: Five samples of size 3 were collected for a variable measurement. All sample data were greater than or equal to 4.0. The sample means and sample ranges are provided in the following table.
Sample number  1  2  3  4  5
________________________________________
Sample mean  5.0  4.9 5.0 6.0 5.2
Sample range 0.2 0.4 0.1 0.0 0.3

The values of which sample are identical?

A Sample 1

B Sample 2

C Sample 3

D Sample 4

Question: Which of the following charts is used to monitor the total number of defects per unit when a constant subgroup size is employed?

A s-chart

B c-chart

C p-chart

D u-chart

Question: An  -chart is used to monitor the process

A Range

B Median

C Variance

D Mean

Question: Which of the following is a likely cause of the control chart pattern known as a trend?

A Aging equipment

B Change in setup method

C New operator

D A mixture of two materials

Question: Determine the sample standard deviation for the following sample data: 7, 9, 2, 0, 1, and 5.

A 3.347

B 3.266

C 2.993

D 3.578

Question: A p-chart is also called a

A Pre-control chart

B Probability chart

C Fraction defective chart

D Process capability chart

Question: Which of the following pairs of charts are used together?

A  -chart and p-chart

B R-chart and p-chart

C R-chart and s-chart

D  -chart and R-chart

Question: c-charts are based on the _____ probability distribution

A Normal

B Binomial

C Poisson

D Uniform

Question: In an  -chart, the upper control limit is equal to the overall sample mean plus three times the

A Process standard deviation

B Average range

C Standard error of the mean

D Sample variance

Question: A _____ monitors the fraction of nonconforming items.

A p-chart

B x-chart

C s-chart

D c-chart

Question: Which of the following would be used to monitor the number of nonconforming items?

A np-chart

B p-chart

C u-chart

D n-chart

Question: 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 Remain the same distance apart

D Both shift upward

Question: Control limits are often confused with _____.

A Control charts

B Tolerance limits

C Specification limits

D Variance limits

Question: Collecting _____ data is usually easier than collecting _____ data because the assessment can usually be done more quickly by a simple inspection or count.

A Attribute; variable

B Concrete; continuous

C Random; discrete

D Simple; continuous

Question: In the application of control charts, as the sample size is increased

A Type I errors are reduced, and Type II errors are increased

B Type I errors are increased, and Type II errors are reduced

C Both Type I and Type II errors are increased

D Both Type I and Type II errors are reduced

Question: A process is deemed “out of control” when

A Common causes are present

B Special causes are present

C Data varies around the mean

D Random variation is present