Deck 19: Statistical Methods for Quality Control

Question 1

Control charts based on data indicating the presence of a defect or the number of defects are called ______ control charts.

A) attributes
B) variables
C) common-cause
D) assignable-cause

Answer 1

attributes

Question 2

If the calculated lower-control limit of a p chart is negative, _____.

A) a mistake has been made in the calculations
B) use the absolute value of the lower limit
C) it is set to zero
D) None of the answers is correct.

Answer 2

it is set to zero

Question 3

An operating characteristic curve is based on a(n) ________ probability distribution.

A) normal
B) exponential
C) binomial
D) uniform

Answer 3

binomial

Question 4

Quality assurance consists of _____.

A) quality control
B) quality engineering
C) quality assurance
D) both quality control and quality engineering

Question 5

The entire system of policies, procedures, and guidelines established by an organization to achieve and maintain quality is called _____.

A) quality control
B) quality engineering
C) quality assurance
D) both quality control and quality engineering

Question 6

Which of the following is NOT a type of a control chart?

A) p chart
B) x-bar chart
C) R chart
D) All of the answers are correct.

Question 7

Which of the following is a statistical method used in quality control?

A) statistical process control
B) acceptance sampling
C) Both statistical process control and acceptance sampling are correct.
D) None of the answers is correct.

Question 8

The control limits for a p chart are how many standard deviations above and below the proportion defective?

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

Question 9

The general practice in quality control is to set the control chart's upper and lower control limit values equal to the variable's mean value +/- _____.

A) 1 standard deviation
B) 2 standard deviations
C) 2.5 standard deviations
D) 3 standard deviations

Question 10

A control chart that is used when the output of a production process is measured in terms of the proportion defective is a(n) _____ chart.

A) p
B) x-bar
C) R
D) np

Question 11

A control chart used when the output of a process is measured in terms of the mean value of a variable such as a length, weight, temperature, and so on is a(n) _____ chart.

A) p
B) x-bar
C) R
D) np

Question 12

The control limits for an x-bar chart are how many standard deviations above and below the process mean?

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

Question 13

__________ consist(s) of making a series of inspections and measurements to determine whether quality standards are being met.

A) Quality control
B) Quality engineering
C) Quality assurance
D) Both quality control and quality engineering

Question 14

A graphical tool used to help determine whether a process is in control or out of control is a _____.

A) scatter diagram
B) histogram
C) control chart
D) None of the answers is correct.

Question 15

Variations in the quality of production output that are due to factors such as machine tools wearing out are _____.

A) common causes
B) assignable causes
C) control causes
D) None of the answers is correct.

Question 16

A control chart that is used to monitor the range of the measurements in a sample is a(n) _____ chart.

A) p
B) x-bar
C) R
D) np

Question 17

Normal or natural variations in the quality of production output that are due purely to chance are _____.

A) common causes
B) assignable causes
C) control causes
D) None of the answers is correct.

Question 18

If the value of c in a single-stage acceptance sampling plan is increased, with n remaining constant, the probability of accepting the lot _____.

A) increases
B) decreases
C) remains the same
D) might increase or decrease, depending on the percent defective in the lot

Question 19

The sample result plotted on an np control chart is _____.

A) n_p
B) np
C) the number of perfect units in the sample
D) the number of defective units in the sample

Question 20

A control chart that is used to monitor the number of defectives in a sample is a(n) _____ chart.

A) p
B) x-bar
C) R
D) np

Question 21

The Malcolm Baldrige National Quality Award was established in _____.

A) 1954
B) 1971
C) 1987
D) 1993

Question 22

In acceptance sampling, the risk of rejecting a good quality lot is known as _____.

A) consumer's risk
B) producer's risk
C) a Type II error
D) None of the answers is correct.

Question 23

Juran proposed a simple definition of quality: _____.

A) customer satisfaction
B) conformance to specifications
C) fitness for use
D) commitment to excellence

Question 24

DFSS stands for _____.

A) Defects Found Sifting and Sorting
B) Design for Six Sigma
C) Deviation from Specifications and Standards
D) Defer for Statistical Study

Question 25

Consumer's risk is _____.

A) the same concept as the producer's risk
B) a Type II error
C) a Type I error
D) None of the answers is correct.

Question 26

Six Sigma represents a quality level of at most ____ defects per million opportunities.

A) 3.4
B) 6.0
C) 19.7
D) 99.5

Question 27

A group of items such as incoming shipments of raw material is called _____.

A) a sample plan
B) an incoming control
C) a lot
D) None of the answers is correct.

Question 28

The maximum number of defective items that can be found in the sample and still lead to acceptance of the lot is _____.

A) the upper control limit
B) the lower control limit
C) the acceptance criterion
D) None of the answers is correct.

Question 29

When a Motorola executive said "That evaluation is … perhaps the most cost-effective, value-added business consultation available anywhere in the world today" he was referring to _____.

A) ISO 9000 standards
B) the Six Sigma philosophy
C) Deming's 14 points
D) the Malcolm Baldrige Quality Award

Question 30

The second stage of a two-stage acceptance sampling plan is executed when the first-stage result is _____.

A) x₁ > c₁
B) c₁ < x₁ < c₂
C) x₁ > c₂
D) x₁ > c₁ + c₂

Question 31

The control limits for an np chart are how many standard deviations above and below the expected number of defectives?

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

Question 32

In contrast to Deming's philosophy, which required a major cultural change in the organization, Juran's programs were designed to improve quality by _____.

A) working within the current organizational system
B) reducing the number of levels in the organizational structure
C) changing customer perception and expectations
D) identifying and replacing the most counterproductive employees

Question 33

The three quality processes on which Juran's approach to quality focused include all of the following EXCEPT quality_____.

A) planning
B) execution
C) control
D) improvement

Question 34

Accepting a good-quality lot would be a _____.

A) Type I error
B) Type II error
C) correct decision
D) None of the answers is correct.

Question 35

A form of acceptance sampling in which more than one sample or stage is used is called a _____.

A) single-sample plan
B) multiple-sampling plan
C) multinomial sampling plan
D) None of the answers is correct.

Question 36

Rejecting a poor-quality lot would be a _____.

A) Type I error
B) Type II error
C) correct decision
D) None of the answers is correct.

Question 37

A statistical procedure in which the number of defective items found in a sample is used to determine whether a lot should be accepted or rejected is called _____.

A) statistical process control
B) acceptance sampling
C) quality assurance
D) a control chart

Question 38

In acceptance sampling, the risk of accepting a poor quality lot is known as _____.

A) consumer's risk
B) producer's risk
C) a Type I error
D) None of the answers is correct.

Question 39

Producer's risk is _____.

A) the same as the consumer's risk
B) a Type II error
C) a Type I error
D) None of the answers is correct.

Question 40

A graph showing the probability of accepting the lot as a function of the percent defective in the lot is _____.

A) a power curve
B) a control chart
C) an operating characteristic curve
D) None of the answers is correct.

Question 41

The two general classifications of attributes in quality control are _____.

A) random and predictable
B) controllable and uncontrollable
C) variable and constant
D) defective and nondefective

Question 42

If the value of c in a single-stage sampling plan is increased, with n remaining constant, the probability of accepting the lot _____.

A) increases
B) decreases
C) is unchanged
D) might increase or decrease, depending on the lot percent defective

Question 43

We can examine the effect of the sampling plan on both types of risks by varying the assumed _____.

A) percentage of defective items in the lot
B) number of defective items in the sample
C) probability of accepting the lot
D) number of units in the lot

Question 44

When only common cause variation is present in a process, _____.

A) no changes or adjustments are necessary
B) we conclude the process is out of control
C) human error is the sole source of variation
D) the source of the variation is easily identified

Question 45

The sample result plotted on a p chart is the _____.

A) proportion nondefective
B) passing (inspection) percentage
C) proportion defective
D) number of defectives

Question 46

Which of the following observed on a control chart suggests a process that is NOT in control?

A) Points follow a smooth pattern from the lower control limit to the upper control limit.
B) The number of points above and below the center line is about the same.
C) Points fall randomly above and below the center line.
D) No points are outside the control limits.

Question 47

Heavy emphasis on statistical analysis and careful measurement are closely associated with _____.

A) total quality
B) ISO 9000
C) the Baldrige National Quality Award
D) Six Sigma

Question 48

Control charts based on data that can be measured on a continuous scale are called _____ control charts.

A) normal
B) variables
C) attributes
D) precision

Question 49

In practice, it is common to use the sample _____ to estimate the process _____.

A) variances, range
B) means, variance
C) standard deviations, mean
D) ranges, standard deviation

Question 50

Process control and acceptance sampling procedures are most closely related to _____.

A) linear regression procedures
B) interval estimation procedures
C) hypothesis testing procedures
D) analysis of variance procedures

Question 51

The process mean and standard deviation can be estimated by using samples that are selected from the process when _____.

A) it has only assignable-cause variation
B) its output is uniformly distributed
C) it is assumed to be operating in control
D) it is operating at peak capacity