Deck 4: Statistical Process Control

Question 1

Variable control charts are used for quantitative measures such as weight or time.

Answer 1

True

Question 2

Common cause (random)variation provides evidence that the process is not in control.

Answer 2

False

Question 3

Statistical process control involves monitoring and controlling a process to prevent poor quality.

Answer 3

True

Question 4

An x-bar and R-chart constructed to monitor and control a process use the same raw data.

Question 5

Process control is achieved by taking periodic samples from a process and plotting the sample points on a chart to determine if the process is within control limits.

Question 6

A process that is determined to be in control contains no variation.

Question 7

Statistical process control is based on a philosophy of inspection as opposed to prevention.

Question 8

Two types of variation associated with the output of a process are common cause (random)and special cause (nonrandom).

Question 9

A variable measure classifies while an attribute measure quantifies.

Question 10

A p-chart is used to monitor the proportion defective in the output of a process.

Question 11

When a control chart detects no special cause (nonrandom)variation in a process,the upper and lower control limits are the same value.

Question 12

Attribute control charts are used to monitor descriptive characteristics of the output of a process rather than measurable characteristics.

Question 13

With a c-chart,the sample size is small and may contain only one item.

Question 14

Control limits are based on the special cause (nonrandom)variation inherent in a process.

Question 15

The formula used to determine the upper and lower control limits are based on product specification limits.

Question 16

The range is the difference between the smallest and largest values in a sample.

Question 17

It is sometimes not necessary to determine new control limits after special cause (nonrandom)variation has been identified if the source has been eliminated without changing the process.

Question 18

One goal of statistical process control is to prevent a process from producing items that have to be scrapped or reworked.

Question 19

Variable control charts are used to monitor measurable characteristics of a process's outputs rather than descriptive characteristics.

Question 20

After special cause variation is detected,the focus changes to identifying the root cause of the variation and eliminating it.

Question 21

A process capability ratio greater than one shows that a process is capable of producing output within its specification limits.

Question 22

For a given process,the process capability ratio is not related to its specification limits.

Question 23

Tolerances or specification limits are allowable variation prescribed in a product design.

Question 24

The popularity of Excel and other data analysis software has been a major factor in the increased use of statistical process control.

Question 25

If the points plotted on a control chart display a pattern,it is called a run.

Question 26

The process capability index indicates how much a process mean differs from the target specification value.

Question 27

A control chart is in control when the plot of the sample points exhibits a pattern.

Question 28

Process control charts are often used at a critical point after which it is difficult to correct or rework the process output.

Question 29

A pattern test can identify an out-of-control process even if all sample points are within control limits.

Question 30

One advantage of using a pattern test is that special cause variations may be identified before any points are plotted outside the control limits.

Question 31

It is possible to have low variation within samples while at the same time having high variation between sample means.

Question 32

All processes contain a certain amount of variation in their output.

Question 33

When constructing a control chart for the first time,all points should be within the control limits indicating the process is in control.

Question 34

Which of the following could be responsible for variability that is special cause (nonrandom)?

A)Broken machinery.
B)Defective parts and materials.
C)Operator error.
D)All these answer choices are correct.

Question 35

If a sample point plotted on a control chart is outside the control limits

A)the evidence indicates the process is in control.
B)the evidence indicates the process is out of control.
C)the evidence is inconclusive.
D)None of these answer choices is correct.

Question 36

The range measures the variation within samples versus the variation between samples.

Question 37

A sequence of sample points that display a pattern is known as a run.

Question 38

Tolerances reflect the amount of common cause variation allowed in a process.

Question 39

Control charts visually show when a process is not within statistical control limits.

Question 40

Statistical process control can prevent poor quality before it occurs if a pattern is evident in the plotted points.

Question 41

Which of the following services can be measured and monitored with control charts?

A)Hospitals
B)Airlines
C)Banks
D)All these answer choices are correct.

Question 42

A control chart that uses the actual number of defects per item to monitor a process is known as a

A)p-chart
B)c-chart
C)R-chart
D) -chart

Question 43

A variable measure is a product characteristic such as

A)color.
B)smoothness.
C)temperature
D)good taste

Question 44

If the quality of a process's output is determined by classifying the output as being defective or not defective,use a(n)________control chart.

A)
B)R
C)c
D)p

Question 45

Control charts are typically used at the ___________ of a process.

A)beginning.
B)middle.
C)end.
D)All these answer choices are correct.

Question 46

Special cause (nonrandom)variation in a process is more likely to be detected with

A)wider control limits
B)narrow control limits
C)wider specification limits
D)narrow specification limits

Question 47

Which of the following is not a characteristic of a control chart?

A)the centerline is determined using special cause (nonrandom)variations.
B)the upper and lower control limits are based on special cause (nonrandom)variation.
C)the centerline is determined by using the target value.
D)None of these answer choices is correct.

Question 48

The formulas for determining the upper and lower control limits are based on the number of standard deviations,z,from the process average.Management usually selects a z value of _______.

A)one
B)two
C)three
D)six

Question 49

A company randomly selects 100 light bulbs every day for 40 days from its production process.If 600 defective light bulbs are found in the sampled bulbs then the 3-sigma lower control limit would be

A)0.0357
B)0.0429
C)0.1500
D)0.1857

Question 50

When a control chart is first developed,if the process is found to be out of control,

A)the control chart can be utilized.
B)the control chart should not be utilized until more samples are taken,
C)the process should be examined and corrections made before a new control chart is constructed.
D)the process should be replaced by a new process.

Question 51

Which of the following control charts are based on sample sizes as small as one?

A)
B)R
C)c
D)p

Question 52

Common (random)variation of a process depends on all the following except

A)errors due to lack of training.
B)the equipment and machinery used.
C)the operator.
D)system used for measurement.

Question 53

Four common types of control charts include all of the following except:

A) -chart
B)t-chart
C)p-chart
D)c-chart

Question 54

Which of the following statements concerning control chart limits is true?

A)the smaller the value of z,the more narrow the control limits are and the more sensitive the chart is to changes in the production process
B)the larger the value of z,the more narrow the control limits are and the more sensitive the chart is to changes in the production process
C)the smaller the value of z,the wider the control limits are and the less sensitive the chart is to changes in the production process
D)the larger the value of z,the more narrow the control limits are and the less sensitive the chart is to changes in the production process

Question 55

The basic purpose of control charts include(s)

A)establishing control limits for a process.
B)monitoring the process to indicate when it is out of control.
C)both establishing control limits for a process and monitoring the process to indicate when it is out of control are basic purposes.
D)None of these answer choices is correct.

Question 56

Which of the following control charts is based on the number of defects within a sample?

A)
B)R
C)c
D)p

Question 57

A company randomly selects 100 light bulbs every day for 40 days from its production process.If 600 defective light bulbs are found in the sampled bulbs then the estimate for the average percent defective would be

A)6.667
B)0.167
C)0.150
D)0.250

Question 58

An attribute measure is a product characteristic such as

A)weight.
B)color.
C)length.
D)time.

Question 59

Which of the following is not a primary purpose of statistical process control?

A)to establish control limits
B)to detect special cause variations
C)to identify specification limits
D)to determine when a process is not in control

Question 60

Which of the following control charts is used to monitor the percent of defective items within a sample?

A)
B)R
C)c
D)p

Question 61

Consider a production process that produces batteries.A quality engineer has taken 20 samples each containing 100 batteries.The total number of defective batteries observed over the 20 samples is 200.The sample standard deviation is

A)0.03
B)0.04
C)0.05
D)0.10

Question 62

Pizazz manufactures a 5.0 oz.energy drink of the same name.Because the cans are so small,consumers are concerned that they are not receiving the full 5 ounces in each can.A quality engineer at the company is charged with analyzing the filling process and ensuring accurate readings.On 15 different occasions over the past month,she has taken a sample of 6 energy drinks off the production line and recorded their weight.If the sum of the sample means is 80.20 ounces and the sum of the sample ranges is 12.68 ounces,the UCL for an R-chart of this process would be

A)0.0
B)1.0
C)1.7
D)2.4

Question 63

Consider a production process that produces batteries.A quality engineer has taken 20 samples each containing 100 batteries.The total number of defective batteries observed over the 20 samples is 200.The centerline for the control chart constructed using z equal to two is

A)0.03
B)0.04
C)0.05
D)0.10

Question 64

Consider a production process that produces batteries.A quality engineer has taken 20 samples each containing 100 batteries.The total number of defective batteries observed over the 20 samples is 200.The UCL for the control chart constructed using two sigma is

A)0.088
B)0.094
C)0.104
D)0.160

Question 65

Easy Tax is a service company that prepares tax returns.An outside auditor has examined 20 samples each containing one completed tax return.The total number of defects observed over the 20 samples is 200.The LCL for the control chart constructed using three sigma is

A)-1.6
B)0.4
C)3.3
D)6.5

Question 66

Consider a production process that produces tires.A quality engineer has taken 15 samples,each containing 200 tires.The total number of defective tires over the 15 samples is 340.The centerline for the control chart is

A)0.08
B)0.11
C)0.16
D)0.21

Question 67

Marble Inc.makes countertops from a variety of high-end materials.To monitor the quality of its production processes the company randomly selects one countertop and counts the number of blemishes.The results for ten samples are shown below: Given the sample information above,the average number of defects per unit for this process would be

A)160
B)80
C)16
D)10

Question 68

Consider a production process that produces tires.A quality engineer has taken 15 samples,each containing 200 tires.The total number of defective tires over the 15 samples is 340.The LCL for the control chat constructed using two sigma is
E)0.022
F)0.036
G)0.048 h.0.066

Question 69

Consider a production process that produces tires.A quality engineer has taken 15 samples,each containing 200 tires.The total number of defective tires over the 15 samples is 340.The UCL for the control chart constructed using two sigma is

A)0.025
B)0.094
C)0.122
D)0.154

Question 70

Pizazz manufactures a 5.0 oz.energy drink of the same name.Because the cans are so small,consumers are concerned that they are not receiving the full 5 ounces in each can.A quality engineer at the company is charged with analyzing the filling process and ensuring accurate readings.On 15 different occasions over the past month,she has taken a sample of 6 energy drinks off the production line and recorded their weight.If the sum of the sample means is 80.20 ounces and the sum of the sample ranges is 12.68 ounces,what is the centerline of an R-chart for this process?

A).50
B).85
C)1.20
D)1.55

Question 71

Easy Tax is a service company that prepares tax returns.An outside auditor has examined 20 samples each containing one completed tax return.The total number of defects observed over the 20 samples is 200.The centerline for the control chart constructed is

A)5
B)10
C)15
D)20

Question 72

Consider a production process that produces batteries.A quality engineer has taken 20 samples each containing 100 batteries.The total number of defective batteries observed over the 20 samples is 200.The LCL for the control chat constructed using two sigma is

A)0.01
B)0.04
C)0.12
D)0.16

Question 73

Pizazz manufactures a 5.0 oz.energy drink of the same name.Because the cans are so small,consumers are concerned that they are not receiving the full 5 ounces in each can.A quality engineer at the company is charged with analyzing the filling process and ensuring accurate readings.On 15 different occasions over the past month,she has taken a sample of 6 energy drinks off the production line and recorded their weight.If the sum of the sample means is 80.20 ounces and the sum of the sample ranges is 12.68 ounces,the UCL for an R-chart of this process would be

A)0.0
B)1.0
C)1.7
D)2.4

Question 74

Marble Inc.makes countertops from a variety of high-end materials.To monitor the quality of its production processes the company randomly selects one countertop and counts the number of blemishes.The results for ten samples are shown below: Given the sample information above,the LCL using sigma = 3 for this process would be

A)12
B)8
C)4
D)0

Question 75

Which of the following control charts are often based on sample sizes equal to or larger than one hundred?

A)
B)R
C)c
D)p

Question 76

Marble Inc.makes countertops from a variety of high-end materials.To monitor the quality of its production processes the company randomly selects one countertop and counts the number of blemishes.The results for ten samples are shown below: Given the sample information above,the UCL using sigma = 3 for this process would be

A)36
B)32
C)30
D)28

Question 77

Consider a production process that produces tires.A quality engineer has taken 15 samples,each containing 200 tires.The total number of defective tires over the 15 samples is 340.The sample standard deviation is

A)0.005
B)0.011
C)0.022
D)0.028

Question 78

Easy Tax is a service company that prepares tax returns.An outside auditor has examined 20 samples each containing one completed tax return.The total number of defects observed over the 20 samples is 200.The UCL for the control chart constructed using three sigma is

A)19.6
B)26.7
C)33.5
D)50.0

Question 79

Easy Tax is a service company that prepares tax returns.An outside auditor has examined 20 samples each containing one completed tax return.The total number of defects observed over the 20 samples is 200.The standard deviation for the control chart is

A)2.2
B)3.2
C)3.9
D)4.5

Question 80

Marble Inc.makes countertops from a variety of high-end materials.To monitor the quality of its production processes the company randomly selects one countertop and counts the number of blemishes.The results for ten samples are shown below: Given the sample information above,the standard deviation of the number of defects for this process would be

A)16
B)10
C)4
D)0