Deck 9: Quality Control and Improvement

Question 1

For which of the following would a p-chart be used?

A)Monitor dispersion in sample data
B)Measure the number of defects per unit
C)Measure the central tendency
D)Measure the fraction defective

Answer 1

Measure the fraction defective

Question 2

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

Answer 2

All of the above

Question 3

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

Answer 3

a,b,and c

Question 4

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 5

A complete system of quality control:

A)Is defined by critical control points,inspectors,measurements,costs,and other considerations
B)Involves a zero defects philosophy
C)Requires a continuous scale for measurement of defects
D)Must include both variable and attribute measurements

Question 6

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 7

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 8

Which of the following statements is NOT true about six sigma quality?

A)Six sigma results in 3.4 ppm defects
B)Six sigma corresponds to 3 standard deviations on either side of the mean
C)Six sigma can be applied to administrative and service processes as well
D)Motorola invented the term "six sigma quality" in the mid-80s

Question 9

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 10

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 11

A Pareto chart:

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

Question 12

The appearance of a restaurant meal that is not satisfactory is an example of:

A)Variable measurement
B)Mean chart
C)Range chart
D)Attribute measurement
E)None of the above

Question 13

Using the information from question 8,what is the upper control limit for the range chart?

A)57.7 lbs
B)211.5 lbs
C)317.25 lbs
D)86.55 lbs

Question 14

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 15

A process control chart:

A)Assumes that 99.74% of special cause variation will fall between upper and lower limits
B)Has upper and lower control limits set at $\pm$ 2 standard deviations from the center line
C)Separates the assignable cause of variation from the common cause of variation
D)Assigns causes of variation to operator,machine,or material

Question 16

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)All of the above are true

Question 17

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

Question 18

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 19

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 20

One of the earliest steps in designing a quality control system is to decide on:

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 on their own work

Question 21

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). $$\begin{array} { | c | c | c | c | c | c | } \hline \text { Bottle } & \text { Sarnple 1 } & \text { Sarnple 2 } & \text { Sarnple 3 } & \text { Sarnple 4 } & \text { Sarnple 5 } \\\hline 1 & 11.8 & 12.0 & 11.8 & 11.9 & 10.7 \\\hline 2 & 12.1 & 12.0 & 11.8 & 12.0 & 11.2 \\\hline 3 & 12.0 & 11.9 & 11.9 & 11.8 & 11.9 \\\hline 4 & 12.2 & 11.8 & 11.7 & 11.9 & 11.7 \\\hline\end{array}$$

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 22

If failure costs were very high,a company would still use inspection.

Question 23

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.Suppose 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 24

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

Question 25

Lean is another term for Six Sigma process improvement.

Question 26

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

Question 27

There are two indicators of a process shift-points outside the control limits and an upward or downward trend in the process average.

Question 28

List and explain the five steps of the DMAIC process.

Question 29

Name the seven tools of quality that are typically used in a manufacturing process.Could all of these tools be applied to service operations? Suggest some possible service operations scenarios wherein we could apply all/some of these tools.

Question 30

Lean projects are usually simpler than six sigma projects.

Question 31

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

Question 32

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

Question 33

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

Question 34

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

Question 35

Six Sigma efforts are aimed at eliminating waste.

Question 36

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

Question 37

The central tendency (mean)of the process is the only information needed to determine if the process is in a state of control.

Question 38

"A production process delivers 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.