Deck 9: Quality Control and Improvement

Question 1

Generally,two types of data may be collected from sampling at an inspection point.These two types of data are

A) variable and attribute data.
B) variable and conditional data.
C) constant and attribute data.
D) constant and conditional data.

Answer 1

variable and attribute data.

Question 2

A Pareto diagram

A) shows causes and effects of quality problems.
B) shows the prevalence of the various types of defects that have been found.
C) is not useful when first studying a quality problem.
D) has both upper and lower specification limits.

Answer 2

shows the prevalence of the various types of defects that have been found.

Question 3

The chair of the Quality Department at Motorola University wants to construct a p-chart for determining whether the four faculty members teaching the course are in a state of control concerning the number of students who fail in the course.Accordingly,the chair sampled 500 final grades from last year for each instructor,and computed the number of failures per instructor as 13,11,0,and 16 respectively.Compute the upper and lower standard control limits for this chart.

A) 0.9500 and 0.0500.
B) 0.0600 and 0.1400.
C) 0.0388 and 0.0012.
D) None of the above.

Answer 3

0.0388 and 0.0012.

Question 4

A machining process is capable of producing a component with an average specification of 5 inches and a process standard deviation of 0.1 inch.Supposing the customer accepts the component as long as it falls between 4.8 inches and 5.2 inches,then the process capability is

A) 1.333.
B) 1.5.
C) 0.667.
D) 1.0.

Question 5

Which of the following quality control sample statistics indicates a quality characteristic that is an attribute?

A) Mean
B) Proportion
C) Variance
D) Standard deviation

Question 6

Which of the following is a critical inspection point where inspection and testing of products occur in a quality control system?

A) Just prior to an irreversible operation (such as drilling).
B) Just prior to a masking operation (an operation that may hide a defect, such as painting or plating).
C) Just prior to packaging and shipping a finished product.
D) All of the above.

Question 7

Of the four choices below,which is the earliest step in designing a quality control system?

A) The amount of inspection to use.
B) Who should do the inspection.
C) The type of measurement to be used.
D) Training workers to perform inspection of their own work.

Question 8

Using the same data as in Question 10,what is the lower control limit for a p-chart?

A) .0750
B) .0191
C) .0000
D) .0692

Question 9

A cause-and-effect diagram

A) identifies common causes of quality defects .
B) is often used in conjunction with a Pareto chart.
C) is also called a fishbone diagram.
D) has all of the above features.

Question 10

Which of the following techniques are used for continuous improvement?

A) Pareto charts.
B) Cause-and-effect diagrams.
C) Process control charts.
D) All of the above

Question 11

Sampling inspection by attributes

A) means each item sampled is classified as defective or not defective based on quality standards.
B) could be used together with process control and variable measurement as part of a quality control system.
C) utilizes a discrete scale of measurement.
D) a, b, and c.

Question 12

The ability of the process to meet,or exceed,its specifications can be determined by

A) Pareto charts.
B) cause-and-effect diagrams.
C) histograms.
D) C_p index.

Question 13

A process for filling liquid laundry detergent bottles monitors the volume in each bottle.The operations manager has taken 5 samples with 4 observations (bottles)in each sample to determine if the variation in volume is reasonable.The measurement unit is fluid ounces.Calculate the center line for a process control chart that indicates whether the variation within samples is reasonable (in a state of control).

A) >1.0.
B) Between 0 and 1.0.
C) Less than 0.
D) There is not enough information to determine the correct response.

Question 14

Which of the following statements about process capability is accurate?

A) C_pk is a better measure of process capability than C_p.
B) C_p is exactly equal to C_pk when the mean is centered in the specification limits.
C) Given the same process, C_pk is always less than or equal to C_p.
D) All of the above are accurate.

Question 15

The figure shown below represents a control chart determined from attribute data.Given this chart and the plotted observations,the most appropriate action would be

A) take immediate action to identify potential causes of the variation.
B) decrease the confidence interval for the control chart.
C) do nothing because the process appears to be operating in control.
D) increase the confidence interval for the control chart.

Question 16

Suppose that you have taken 30 samples of 200 units each and calculated the proportion defective as p = .075.What is the upper control limit for a p-chart?

A) .2192
B) .0191
C) .1309
D) .7500

Question 17

Which of the following is/are assumption(s)of process control?

A) Random variability cannot be eliminated unless the process is redesigned.
B) Common causes represent random variability.
C) Production processes are not usually found in a state of control.
D) All of the above.

Question 18

Which of the following statements about process quality control is NOT true?

A) Assignable cause variation is also referred as special cause variation.
B) An observation outside the control limits is an example of a special cause of variation.
C) Common cause variation can be eliminated from the process by removing the potential causes.
D) The control limits will include 99.74% of the population under the normal probability distribution assuming that the process is in control.

Question 19

Regarding the design of a quality control system,which of the following statements is correct?

A) First, decide on the type of measurement required, then who will collect the data.
B) First, decide on the amount of inspection needed, then critical points and type of measurement needed.
C) First, decide who will be the inspector, then that person determines the critical points and collects the data.
D) Decide on the critical points first, then the type and amount of measurement needed.

Question 20

Suppose that a process is in a state of control and we have the following information for a human weights measurement study: Average weight of males in the study = 150 lbs.
Average range of the male weights = 100 lbs.
A₂ = .577
D₃ = 0
D₄ = 2.115
What is the upper control limit for the average (mean)chart?

A) 207.7 lbs
B) 92.3 lbs
C) 361.5 lbs
D) 175 lbs

Question 21

Which of the following statements is true?

A) For a variables control chart, n should be fairly large, frequently 50-300 observations.
B) For an attribute control chart, n is typically 5-10 observations, and rarely larger than 24.
C) For an attribute control chart, n should be large enough to include at least one defective unit.
D) None of the above.

Question 22

Range charts are used to evaluate

A) the variability of data within samples for variable data.
B) the variability of data within samples for attribute data.
C) the variability of data among (central tendency) samples.
D) the variability of process capability.

Question 23

Consider the following statements: (1)The primary focus of lean is to reduce waste.
(2)The primary focus of six sigma is to reduce defects.

A) Only statement (1) is correct.
B) Only statement (2) is correct.
C) Both statements are correct.
D) Neither statement is correct.

Question 24

One of the first stages in any statistical process control program is to ascertain that the equipment utilized for an operation is inherently capable of producing within the design tolerance.For a particular lathe operation,run under controlled conditions so that no assignable causes of variation have been introduced,the outside diameter of each sampled part was measured,and the operator found that the standard deviation was 0.0075 centimeters (cm).What is the process capability if the upper specification limit is 7.508 cm and the lower specification limit is 7.388 cm?

A) 2.67
B) 1.00
C) 0.375
D) None of the above.

Question 25

A production process delivers an unexpectedly large amount of scrap products.Top management has discovered that improper machine maintenance is the reason behind this failure.The above statement is an example of a special cause of variation.

Question 26

Which of the following is the best description of quality control?

A) The use of mass inspection in a process to ensure quality and meet customer requirements.
B) The continuous improvement of a process to better address customer needs.
C) The stabilization and maintenance of a process to produce consistent output.
D) Constancy of purpose toward improvement of the product or service.

Question 27

Which of the following statements is NOT correct?

A) Control limits represent the "voice of the process."
B) The average of the measurement data collected is the same as the center line.
C) Six sigma equates to 99.74% of output within the control limits.
D) A normal distribution of a process under control will include a very small amount outside the control limits.

Question 28

Which of the following is the best description of variables data?

A) Number of students more than six feet tall in a classroom.
B) Ratio of damaged apples to perfect apples in a shipment.
C) Downward force required to cause a critical part to fail during a quality test.
D) Adequate strength of adhesive applied between two components.

Question 29

The seven tools of quality control include all of the following EXCEPT

A) flowcharts.
B) Pareto charts.
C) DMAIC charts.
D) scatter diagrams.

Question 30

__________ are ideal for monitoring continuous data.

A) p-charts
B) x-bar and R-charts
C) Ishikawa charts
D) None of the above

Question 31

A manufacturer of television wall mounts would like to make a chart to monitor the percentage of defective mounting brackets due to problems with drilled holes.These holes may be defective because they are off-center,out of round,or not drilled.Five samples,each of size 100,have been taken from the production process and the discrepancies are as follows: Using this information and a 3 standard deviation chart,the upper control limit is

A) 0.0025.
B) 0.0420.
C) 0.0602.
D) 0.102.

Question 32

If the population of items produced does not meet or exceed the upper and low specification limits (all items produced are well within specification limits),the process capability index,Cp,will be

A) less than 0.0.
B) between 0.0 and 1.0.
C) equal to 1.0.
D) greater than 1.0.

Question 33

Which statement best represents the key assumption(s)of process control?

A) Most processes are affected by common and special causes of variation.
B) It is easier to address common cause variation than special cause variation.
C) Most processes are found to be in control.
D) All of the above.

Question 34

Attribute control occurs when the product characteristic is measured on a continuous scale.

Question 35

Put the following statements in the correct order: (1)Decide who should do the inspection.
(2)Decide on the type of measurement.
(3)Decide on the amount of inspection.
(4)Decide on the critical points requiring inspection.

A) 4, 1, 2, 3.
B) 4, 2, 3, 1.
C) 1, 2, 3, 4.
D) 2, 4, 1, 3.

Question 36

Which of the following makes the most sense,given today's view of quality control?

A) Full-time, certified inspectors are preferred for all critical control points.
B) The department receiving the inputs is the preferred location for the critical control point.
C) The person doing the job should have the responsibility of inspection.
D) The manager of the process should be inspecting quality at critical points.

Question 37

Which of the following statements about six sigma is NOT correct?

A) The six sigma approach is suited only for manufacturing processes.
B) Six sigma programs employ full-time specialists called black belts.
C) Six sigma employs a structured process improvement technique.
D) Data and metrics are vital in a six sigma approach.

Question 38

A brewer bottles beer labeled "net weight 12 ounces." A production employee pulled 20 random samples of 5 bottles each throughout the day and found that the average weight is exactly 12 ounces and the average range of the samples is 0.25 ounce.What is the lower control limit for the averages chart for this process?

A) 12.144 ounces.
B) 11.955 ounces.
C) 11.856 ounces.
D) None of the above.

Question 39

The work of 20 claims processors is sampled and examined for errors.100 claims are randomly pulled for each processor with the results shown below.What is the upper limit of the control chart?

A) 0.059 (or 0.06).
B) 0.084 (or 0.08).
C) 0.099 (or 0.10).
D) None of the above.

Question 40

Which of the following statements is NOT correct?

A) Six sigma projects require measurement of financial impact be closely tracked, compared to lean projects that do not insist on financial tracking.
B) Six sigma relies more on dedicated experts to guide projects as compared to lean.
C) Lean projects tend to be smaller and simpler compared to six sigma projects.
D) Lean projects tend to support strategic priorities more than is the case for six sigma projects.

Question 41

Name the seven tools of quality control typically used in process improvement.Could all of these tools be applied to service operations?
Suggest some possible service operations scenarios wherein we could apply all or some of these tools.

Question 42

The C_p measure requires the process to be centered for an accurate measure of process capability.

Question 43

List and explain the five steps of the DMAIC process.

Question 44

Surveys indicate that p charts are used more frequently than average (mean)and range charts are used.

Question 45

Lean is another term for six sigma process improvement.

Question 46

Lean projects are usually simpler than six sigma projects.

Question 47

Six sigma projects are typically managed by workers certified as black belts.

Question 48

In process capability analysis,the standard deviation ( $\sigma$ )refers to the standard deviation of sample measures.

Question 49

The seven tools of quality control are equally applicable to both manufacturing and service industries.

Question 50

The quality tool that shows the relationship between two variables is a histogram.