Deck 6: Statistical Quality Control

Question 1

The A₂ factor includes how many standard deviations of ranges?

A) 1
B) 2
C) 3
D) 4
E) 6

Answer 1

C

Question 2

The range is an example of what?

A) Traditional statistical tools
B) Fishbone diagramming
C) Acceptance sampling
D) Experimental design
E) Statistical process control

Answer 2

A

Question 3

Causes of variation that can be identified and eliminated are called what?

A) Random
B) Assignable
C) Identifiable
D) Stochastic
E) Common

Answer 3

B

Question 4

What technique determines whether a batch of goods should be accepted or rejected?

A) Statistical process control
B) Acceptance sampling
C) Fishbone diagramming
D) Scatter plotting
E) Experimental design

Question 5

P-charts are used to measure:

A) continuous variation
B) intermittent random variation
C) proportion of items in a sample that is defective
D) the count of defective parts
E) proportion of items in a sample that are good

Question 6

An OC curve is an example of what?

A) Traditional statistical tools
B) Fishbone diagramming
C) Acceptance sampling
D) Experimental design
E) Statistical process control

Question 7

What measures the central tendency of a set of data?

A) Coefficient of variation
B) Variance
C) Standard deviation
D) Mean
E) Range

Question 8

All processes will have what type of variation?

A) Random
B) Assignable
C) Identifiable
D) Stochastic
E) Common

Question 9

For the standard normal distribution, how much confidence is provided within 2 standard deviations above and below the mean?

A) 97.22%
B) 95.44%
C) 99.74%
D) 99.87%
E) 90.00%

Question 10

The standard deviation is an example of what?

A) Traditional statistical tools
B) Fishbone diagramming
C) Acceptance sampling
D) Experimental design
E) Statistical process control

Question 11

What technique answers the question of whether the process is functioning properly or not?

A) Fishbone diagramming
B) Acceptance sampling
C) Statistical process control
D) Scatter plotting
E) Experimental design

Question 12

An x-bar chart is an example of what?

A) Traditional statistical tools
B) Fishbone diagramming
C) Acceptance sampling
D) Experimental design
E) Statistical process control

Question 13

Variation in the production process leads to:

A) quality defects
B) process improvement opportunities
C) quality improvements
D) product consistency
E) service improvements

Question 14

A c-chart is an example of what?

A) Traditional statistical tools
B) Fishbone diagramming
C) Acceptance sampling
D) Experimental design
E) Statistical process control

Question 15

Which of the following is not associated with descriptive statistics?

A) mean
B) standard deviation
C) range
D) proportion
E) measure of the distribution of data

Question 16

What measures the difference between the largest and smallest observations in a set of data?

A) Range
B) Coefficient of variation
C) Coefficient of kurtosis
D) Coefficient of skewness
E) Standard deviation

Question 17

A process chart is a

A) graph that shows how the population was evaluated
B) graph of the population failures
C) graph that shows whether a sample of data falls within assignable causes
D) graph that show whether a sample falls within the common or normal range
E) table showing final inspection results

Question 18

Statistical process control tools are used most frequently because

A) they are mathematically based
B) they are helpful in measuring and evaluating the quality of products
C) they are helpful in measuring and evaluating the customers' needs
D) they are qualitative evaluation techniques
E) they provide a definitive ROI calculation

Question 19

A p-chart is an example of what?

A) Traditional statistical tools
B) Fishbone diagramming
C) Acceptance sampling
D) Experimental design
E) Statistical process control

Question 20

Common causes of variation are also known as __________________________.

A) frequent
B) usual
C) inexpensive
D) ordinary
E) random

Question 21

What is a control chart that monitors changes in the dispersion or variability of a process?

A) x-bar chart
B) R-chart
C) p-chart
D) c-chart
E) OC chart

Question 22

For a p-chart or c-chart, what is the implication of a negative value for the LCL?

A) A calculation error must have occurred.
B) The value of sigma must be reduced.
C) The process has too many errors.
D) The process is in a state of control.
E) The LCL can effectively be rounded up to 0.

Question 23

What is the first step that should be taken if an observation falls below the lower control limit on a control chart?

A) Recalibrate the machine
B) Perform a new process capability study
C) Try a larger standard deviation value
D) Search for assignable causes
E) Nothing-a low value is a "good" thing

Question 24

What are the two types of control charts for attributes?

A) p and c
B) x-bar and p
C) x-bar and R
D) R and c
E) p and R

Question 25

Upper and lower control limits are usually set at $\pm$ how many standard deviations from the mean?

A) 0.5
B) 1.0
C) 2.0
D) 3.0
E) 6.0

Question 26

What are the four most common control charts?

A) x-bar, R, p, c
B) x-bar, R, p, OC
C) x-bar, R, c, OC
D) x-bar, p, c, OC
E) R, p, c, OC

Question 27

What is a control chart that monitors changes in the mean value of a process?

A) x-bar chart
B) R-chart
C) p-chart
D) c-chart
E) OC chart

Question 28

For which of the following would a control chart for attributes not be appropriate?

A) Number of nonfunctioning light bulbs
B) Proportion of broken eggs in a carton
C) Number of rotten apples
D) Number of complaints issued
E) Length of metal rods

Question 29

What are the two types of control charts for variables?

A) p and c
B) x-bar and p
C) x-bar and R
D) R and c
E) p and R

Question 30

Consider a p-chart measuring the percentage of defective light bulbs. If the LCL is .04 and a sample has 1% defects, what is the implication?

A) The process is in a state of control.
B) The process is out of control even though the variation is "good."
C) The value of sigma must be increased.
D) The process has too many errors.
E) A calculation error must have occurred.

Question 31

Assuming that data exhibit a normal distribution, control limits set at $\pm$ 3 standard deviations from the mean capture how much common variation?

A) 50.00%
B) 80.00%
C) 95.44%
D) 99.74%
E) 99.99%

Question 32

What is the term for the probability that a value falling outside the control limits is still due to normal variation?

A) Type I error
B) Type II error
C) Normalization anomaly
D) Beta risk
E) Standard deviation irregularity

Question 33

The different characteristics that can be measured by control charts can be divided into what two groups?

A) Parameters and attributes
B) Variables and attributes
C) Variables and constraints
D) Variables and parameters
E) Attributes and constraints

Question 34

Which of the following would imply that data observations are closely clustered around the mean?

A) Small range and small standard deviation
B) Small range and large standard deviation
C) Large range and small standard deviation
D) Large range and large standard deviation
E) Neither range nor standard deviation has anything to do with "clustering."

Question 35

What is the probability of a Type I error for a control chart with limits set at $\pm$ 3 standard deviations from the mean?

A) 0.00%
B) 0.26%
C) 4.56%
D) 20.00%
E) 50.00%

Question 36

The center line of a control chart represents what?

A) Range
B) Standard deviation
C) Mean
D) Mean divided by standard deviation
E) Skewness

Question 37

What measures symmetry of a distribution?

A) Range
B) Skewness
C) Standard deviation
D) Mean
E) Variance

Question 38

On a control chart, what separates common from assignable causes of variation?

A) x-bar lines
B) Control limits
C) Specification limits
D) Production limits
E) Mean divided by standard deviation

Question 39

What is a control chart that monitors the proportion of defects in a sample?

A) x-bar chart
B) R-chart
C) p-chart
D) c-chart
E) OC chart

Question 40

What is a distribution called when the same numbers of observations are below the mean as are above the mean?
B) Equalized
B) Proportional
C) Wholly Uniform
D) Balanced
E) Symmetric

Question 41

What is the formula for the process capability index C_p?

A) process width / specification width
B) specification width $\times$ process width
C) specification width / Type I error
D) specification width / process width
E) specification width / 99.74%

Question 42

Six-sigma quality implies how many average defects per million?

A) 3.4
B) 6
C) 2600
D) 3 $\sigma$
E) 6 $\sigma$

Question 43

What process capability index (C_p) value implies that the process "exceeds minimal capability?"

A) 0
B) < 1
C) = 1
D) > 1
E) 6 $\sigma$

Question 44

What process width is typically used when computing the process capability index C_p?

A) 1 $\sigma$
B) 2 $\sigma$
C) 3 $\sigma$
D) 4 $\sigma$
E) 6 $\sigma$

Question 45

According to the textbook, the way to reduce the ppm defective is to

A) change product specifications
B) increase process capability
C) increase the number of inspection points.
D) employ more inspectors
E) increase process throughput

Question 46

The person that comes from the top ranks of the organization and is responsible for providing direction and overseeing all aspects of a six-sigma implementation process is called a ________________________.

A) general
B) admiral
C) director
D) producer
E) champion

Question 47

What is a graph that shows the probability or chance of accepting a lot given various proportions of defects in the lot?

A) S curve
B) Z-chart
C) OC curve
D) p-chart
E) R-chart

Question 48

In six-sigma programs, individuals who have extensive training in the use of technical tools and are responsible for carrying out the implementation of Six Sigma are __________________.

A) black belts
B) green belts
C) blue belts
D) red belts
E) white belts

Question 49

According to the text, what percent of defects are consumers generally willing to accept?

A) 1-2%
B) 2-3%
C) 3-4%
D) 4-5%
E) 5-6%

Question 50

What is the relationship between C_p and C_pk?

A) C_p $\ge$ 2 C_pk
B) C_p $\le$ C_pk
C) C_p $\ge$ C_pk
D) C_p $\le$ 2C_pk
E) C_p $\div$ C_pk $\ge$ 3 $\sigma$

Question 51

Product tolerances are often called

A) SPC
B) Product drawings
C) Product descriptions
D) Process capability
E) Product specifications

Question 52

What are preset ranges of acceptable quality characteristics?
B) Control limits.
B) Product specifications.
C) Six-sigma limits.
D) AQC limits.
E) R-chart limits.

Question 53

In six-sigma programs, individuals are given __________________ titles that reflect their skills in the six-sigma process.

A) Olympic medal
B) academic
C) martial arts
D) medieval jousting
E) boxing

Question 54

Single sampling plan is when

A) a non-random sample is drawn from every lot.
B) a random sample is drawn from every lot.
C) a second lot is sampled due to the first sample inconclusive results.
D) only one time is tested.
E) a sample plan used once and discarded.

Question 55

Which company is known for coining the term "six-sigma?"

A) Ford Motor Company
B) Proctor and Gamble
C) IBM
D) Motorola Corporation
E) Hewlett-Packard

Question 56

The Six Sigma approach is organized around a _______ plan known as ________.

A) four step, PDAC
B) four step, DMAC
C) five step PDACR
D) five step DMAIC
E) five step, DMCRA

Question 57

When should 100% inspection be used?

A) Whenever attributes are being measured
B) When the expected cost of a defective item exceeds the cost of inspecting a unit
C) With destructive testing
D) When the cost of inspecting a unit exceeds the expected cost of a defective item
E) 100% inspection should never be used

Question 58

Setting up control charts to monitor whether a process is in control

A) guarantees process capability
B) guarantees process specifications
C) does not guarantee process capability
D) does not guarantee product specification
E) guarantees meeting client needs

Question 59

A process capability index (C_p) value of 1 means that what percent of products produced will fall within the specification limits?

A) 0.26%
B) 90.00%
C) 95.44%
D) 99.74%
E) 100.00%

Question 60

What are the two aspects to implementing the six-sigma concept?

A) numerically controlled machines and inventory management
B) numerically controlled machines and people involvement
C) numerically controlled machines and technical tools
D) technical tools and people involvement
E) inventory management and technical tools

Question 61

An important task in quality control is to find out the range of natural random variation in a process.

Question 62

Statistical quality control is a subset of statistical process control.

Question 63

What program at Intel enforces the policy to make chips in the same way at all facilities?

A) "make-same"
B) "copy-exactly"
C) "duplicate-same"
D) "duplicate-exactly"
E) "one-size-fits-all"

Question 64

Suppose that you have calculated the control limits for a p-chart to be the following:
LCL = 0.02 and UCL = 0.08.
Today, you took 10 samples of 20 units each. The first nine samples each had one defect. The last sample had zero defects. What can you conclude?

A) the process is out of control
B) the process is in a state of control
C) the last sample should be ignored because it was "too good"
D) you calculated the limits incorrectly because the LCL must be either negative or 0
E) the sample size must be increased

Question 65

Suppose that Matt wants to use a process control chart to monitor the number of different types of mistakes that he makes when giving motivational speeches to student groups. Which control chart would be most appropriate?

A) x-bar chart
B) R-chart
C) p-chart
D) c-chart
E) OC chart

Question 66

Suppose that you want to monitor the variability in ounces of a process that fills beer cans. Which control chart would be appropriate?

A) x-bar chart
B) R-chart
C) p-chart
D) c-chart
E) OC chart

Question 67

Each day for two workweeks (10 days total), George weighs 4 bags from that day's production. If the average of the means is 14 oz. and the average range is 0.4 oz., what is the lower control limit for an x-bar chart for this process?

A) 13.7084 oz.
B) 13.8768 oz.
C) 14.2916 oz.
D) 12.8000 oz.
E) 13.5908 oz.

Question 68

Acceptance sampling occurs after the product has been produced.

Question 69

Descriptive statistics are used to describe quality characteristics and relationships.

Question 70

The standard deviation measures the difference between the largest and smallest observations in a set of data.

Question 71

What is the upper control limit for a c-chart if the total defects found over 200 samples equals 32?

A) 1.36
B) 13.75
C) 0.56
D) 25.00
E) 48.97

Question 72

Ritz-Carlton employees are empowered to spend up to how much money on the spot to correct any customer complaint?

A) $25
B) $50
C) $100
D) $1000
E) $2000

Question 73

Which of the following is the least important point to perform inspection?

A) Incoming materials
B) Prior to costly processing
C) Just after costly processing
D) Prior to bottleneck (limited machine capacity) processing
E) After the product is finished

Question 74

What is the lower control limit for a c-chart if the average number of defects found over 320 samples is equal to 16?

A) 6.584
B) 4
C) 20
D) 0
E) 12

Question 75

Suppose that you want to monitor the average ounces of a process that fills beer cans. Which control chart would be appropriate?

A) x-bar chart
B) R-chart
C) p-chart
D) c-chart
E) OC chart

Question 76

Suppose that you want to measure the percentage of candles that are cut longer than 9 inches. Which control chart would be appropriate?

A) x-bar chart
B) R-chart
C) p-chart
D) c-chart
E) OC chart

Question 77

What is the upper control limit for a c-chart if the total defects found over 20 samples equals 150?

A) 7.5
B) 2.739
C) 15.72
D) 20
E) 30

Question 78

If the upper control limit for a c-chart is 28 and the lower control limit is 4, what is the average number of defects per sample?

A) 16
B) 12
C) 5.29
D) 7.29
E) 4

Question 79

The range of a data set is always non-negative.

Question 80

What is the only service company to have won the Malcolm Baldrige National Quality Award twice?

A) Marriott
B) Nordstrom Department Stores
C) Wal-Mart
D) Ritz-Carlton
E) Northwest Airlines