Deck 14: Statistical Process Control

Question 1

Construct an chart and determine whether the process variation is within statistical control.

A machine is supposed to fill cans that contain 12 ounces. Each hour, a sample of four cans is tested; the results of 15 consecutive hours are given below.

Answer 1

The process appears to be within statistical control.

Question 2

A common goal of quality control is to reduce variation in a product or service. List and describe the two types of variability. Give an example of each.

Answer 2

Random variation is due to chance, the variation inherent in any process that is not capable of producing each good
or service exactly the same way every time. Assignable variation results from causes that can be identified.
Examples may vary.

Question 3

Examine the given run chart or control chart and determine whether the process is within statistical control. If it is not, identify which of the three out-of-statistical-control criteria apply.

Answer 3

The process appears to be out of statistical control. There is a cyclical pattern.

Question 4

Construct a run chart for individual values corresponding to the given data. A machine is supposed to fill boxes to a weight of 50 pounds. Every 30 minutes a sample of four boxes is tested; the results are given below.

Question 5

Construct an chart and determine whether the process variation is within statistical control.

A machine that is supposed to fill small bottles to contain 20 milliliters yields the following data from a test of 4 bottles every hour.

Question 6

Define statistically stable (or "within statistical control"). Show examples of run charts which illustrate processes which are not statistically controlled. Discuss the pattern which indicates
the process is not statistically controlled for each example.

Question 7

Use the given process data to construct a control chart for p. A manufacturer monitors the level of defects in the television sets that it produces. Each week, 200 television sets are randomly
selected and tested and the number of defects is recorded. The results for 12 consecutive weeks
are shown below.

Question 8

Are control charts based on actual behavior or on desired behavior? Give an example to illustrate the difference between the two types of behavior.

Question 9

Use the given process data to construct a control chart for p. If the weight of cereal in a particular packet is less than 14 ounces, the packet is considered nonconforming. Each week,
the manufacturer randomly selects 1,000 cereal packets and determines the number that are
nonconforming. The results for 12 consecutive weeks are shown below.

Question 10

Describe the three criteria used to determine if a control chart indicates a process which is not statistically stable.

Question 11

A control chart for R is shown below. Determine whether the process variation is within statistical control. If it is not, identify which of the three out-of-control criteria lead to rejection
of statistically stable variation.

Question 12

Describe an R chart and give an example. What does it attempt to monitor?

Question 13

Provide an appropriate response. Describe what process data are. Why are process data important to businesses? What is a common goal of businesses using quality control?

Question 14

A control chart for is shown below. Determine whether the process mean is within statistical control. If it is not, identify which of the three out-of-control criteria lead to rejection of a statistically stable mean.

Question 15

Sketch a control chart that indicates that a process is not statistically stable due to the run of 8 rule.

Question 16

Examine the given run chart or control chart and determine whether the process is within statistical control. If it is not, identify which of the three out-of-statistical-control criteria apply.

Question 17

Examine the given run chart or control chart and determine whether the process is within statistical control. If it is not, identity which of the three out-of-statistical-control criteria
apply. A run chart for individual values W is shown below. Does there appear to be a pattern
suggesting that the process is not within statistical control? If so, describe the pattern.

Question 18

Describe a run chart and give an example. Refer to the values on each of the axes as you describe the run chart.

Question 19

A control chart for is shown below. Determine whether the process mean is within statistical control. If it is not, identify which of the three out-of-control criteria lead to rejection of a statistically stable mean.

Question 20

Control Chart Constants

A machine is supposed to fill boxes to a weight of 50 pounds. Every 30 minutes a sample of four boxes is tested; the results are given below.

Question 21

A control chart for is shown below. Determine whether the process mean is within statistical control. If it is not, identify which of the three out-of-control criteria lead to rejection of a statistically stable mean.

Question 22

Provide an appropriate response. A common goal of quality control is to reduce variation in a product or service. List and describe the two types of variability. Give an example of each.

Question 23

Examine the given run chart or control chart and determine whether the process is within statistical control. If it is not, identify which of the three out-of-statistical-control criteria apply.

Question 24

Describe the three criteria used to determine if a control chart indicates a process which is not statistically stable.

Question 25

Sketch a run chart that that indicates that a process is not statistically stable due to increasing variation.

Question 26

Match the chart with its characteristic.

Question 27

A control chart for is shown below. Determine whether the process mean is within statistical control. If it is not, identify which of the three out-of-control criteria lead to rejection of a statistically stable mean.

Question 28

Construct an chart and determine whether the process variation is within statistical control.

A machine that is supposed to produce ball bearings with a diameter of 7 millimeters yields the following data from a test of 5 ball bearings every 20 minutes.

Question 29

Use the given process data to construct a control chart for p. A drugstore considers a wait of more than 5 minutes to be a defect. Each week 100 customers are randomly selected and
timed at the checkout line. The numbers of defects for 20 consecutive weeks are given below.

Question 30

Construct an chart and determine whether the process variation is within statistical control.

A machine that is supposed to produce ball bearings with a diameter of 7 millimeters yields the following data from a test of 5 ball bearings every 20 minutes.

Question 31

A control chart for is shown below. Determine whether the process variation is within statistical control. If it is not, identify which of the three out-of-control criteria lead to rejection of statistically stable variation.

Question 32

Describe a p chart and give an example.

Question 33

Examine the given run chart or control chart and determine whether the process is within
statistical control. If it is not, identify which of the three out-of-statistical-control criteria apply.

Question 34

Construct a run chart for individual values corresponding to the given data. A machine that supposed to produce ball bearings with a diameter of 7 millimeters yields the following d from a test of 5 ball bearings every 20 minutes.

Question 35

Use the given process data to construct a control chart for p. A manufacturer monitors the level of defects in the television sets that it produces. Each week, 200 television sets are randomly
selected and tested and the number of defects is recorded. The results for 12 consecutive weeks
are shown below.

Question 36

A run chart for individual values is shown below. Does there appear to be a pattern suggesting that the process is not within statistical control? If so, describe the pattern.

Question 37

A control chart for attributes is to be constructed. limits, a process which has been having a 5% rate of nonconforming items, or a process which
has been having a 10% of nonconforming items? Assume that both processes have the same
sample sizes. For a given sample size, would it be easier to detect a shift from 5% to 10% or a
shift from 10% to 15%? Explain your reasoning.

Question 38

Define statistically stable (or "within statistical control"). Show examples of run charts which illustrate processes which are not statistically controlled. Discuss the pattern which indicates
the process is not statistically controlled for each example.

Question 39

A control chart for is shown below. Determine whether the process mean is within statistical control. If it is not, identify which of the three out-of-control criteria lead to rejection of a statistically stable mean.

Question 40

Examine the given run chart or control chart and determine whether the process is within statistical control. If it is not, identify which of the three out-of-statistical-control
criteria apply.

Question 41

Use the given process data to construct a control chart for p. A drugstore considers a wait of more than 5 minutes to be a defect. Each week 100 customers are randomly selected and timed at the checkout line. The numbers of defects for 20 consecutive weeks are given below. What is the value of the upper control limit?

A) 1
B) 0.0783
C) 0.0622
D) 6.2

Question 42

Which graph using individual data values instead of a process characteristic?

A) p chart
B) Run chart
C) R chart
D)

Question 43

Examine the given run chart or control chart and determine whether the process is within statistical control.

A) The process is within statistical control.
B) The process is not within statistical control.

Question 44

Use the given process data to construct a control chart for p. A candy manufacturer considers a cracked piece of candy to be a defect. Each day 100 candies are randomly selected and checked for cracks. The numbers of defects for 20 consecutive days are given below. What is the value of the center line?

A) 6.6
B) 10
C) 0.066
D) 1.32

Question 45

A _________________ is a sequential plot of individual data values over time. One axis is used for the data values, and the other axis is used for the time sequence.

A) run chart
B) process chart
C) time-process chart
D) flow chart

Question 46

__________________ variation results from causes that can be identified.

A) Random
B) Identifiable
C) Assignable
D) Definable

Question 47

Examine the given run chart or control chart and determine whether the process is within statistical control.

A) The process is within statistical control.
B) The process is not within statistical control.

Question 48

Which type of chart does not have control limits?

A) Run chart
B) R chart
C)
D) p chart

Question 49

The centerline for a control chart for R consists of _______________.

A) the mean of the sample ranges
B) the mean of the sample data
C) the median
D) the standard deviation

Question 50

Examine the given run chart or control chart and determine whether the process is within statistical control.

A) The process is within statistical control.
B) The process is not within statistical control.

Question 51

Consider process data consisting of the amounts of potato chips (in ounces) in randomly selected bags of chips. The process is to be monitored with control charts based on samples of 50 bags randomly selected each day for 15 consecutive days of production. What does denote?

A) The mean of 50 bags.
B) The mean of all 15 sample means.
C) The mean of the ranges for the 15 days.
D) The mean of the standard deviations for the 15 days.

Question 52

A machine is supposed to fill boxes to a weight of 50 pounds. Every 30 minutes a sample of four boxes is tested; the results are given below. What would be the value of the centerline that would be used in creating an R chart?

A) 49.567 pounds
B) 50 pounds
C) 11.00 pounds
D) 12.8000 pounds

Question 53

A machine that is supposed to fill small bottles to contain 20 milliliters yields the following data from a test of 4 bottles every hour. What would be the centerline for a control chart for ?

A) 0.380 milliliters
B) 19.935 milliliters
C) 20.000 milliliters
D) 20.212 milliliters

Question 54

Which type of chart would be best for monitoring the proportion of items that are defective?

A) R chart
B)
C) p chart
D) Run chart

Question 55

Which of the following is not one of the criteria for determining if a control chart indicates that a process is not statistically stable?

A) Exceptional value
B) Upward shift
C) Downward trend
D) Decreasing variation

Question 56

_______________ measurement of a characteristic or good or services that result from some combination of equipment, people, materials, methods, and conditions.

A) Process
B) Service
C) Sequential
D) Material

Question 57

R charts are used to monitor_____________.

A) means
B) proportions
C) variation
D) correlation

Question 58

Control charts are used to monitor changing characteristics of data over ____________.

A) time
B) space
C) distance
D) speed

Question 59

A manufacturer of lightbulbs picks 10 lightbulbs at random each day for quality control. The mean and range (in hours) of the lifetimes of the 10 lightbulbs are calculated. The results for 12 consecutive days are shown in the table below. Construct an R chart to determine whether the process is in statistical control.

A) The process is within statistical control.
B) The process is not within statistical control.

Question 60

Examine the given run chart or control chart and determine whether the process is within statistical control.

A) The process is within statistical control.
B) The process is not within statistical control.