Common Questions v3 ALREADY
PASSED
Variation in production systems that is caused by factors that can be clearly identified and possibly even
managed is called assignable variation. - ANS True
An example of assignable variation in a production system may be that workers are not identically
trained - ANS True
An example of assignable variation in a production system may be that a machine is not adjusted
properly - ANS True
Variation that is inherent in a production process itself is called assignable variation. - ANS False
Variation that is inherent in a production process itself is called common variation. - ANS True
It is impossible to have zero variability in production processes. - ANS True
Genichi Taguchi's view of the cost of quality is that variance is a discontinuous function - ANS False
The capability index is used to gauge economic changes in service systems. - ANS False
Process control is concerned with monitoring quality after the product or service has been produced. -
ANS False
Statistical process control involves testing random samples of output from a process to determine
whether the process is producing items within a preselected range. - ANS True
,Measurement by attributes means taking a sample, measuring the attribute in question, and
determining the level of quality in the population from which the sample was drawn. - ANS False
Attributes are those quality characteristics that are classified as either conforming or not conforming to
specification - ANS True
A p-chart has upper and lower control limits expressed as lines on the chart. As long as the sample
values fall between these two lines, there is no need to investigate process behavior - ANS False
The p-chart is only useful for sampling that deals with continuous variables. - ANS False
The value for "z" used in quality control charts is based on the degree of confidence you want to have in
the resulting UCL and LCL values. - ANS True
If the fraction defective is 0.12 based on a sample size of 16, the standard deviation used in the p-chart
is about 0.08. - ANS True
If the fraction defective is 0.4 based on a sample size of 100, the standard deviation used in the p-chart
is about 0.10. - ANS False
To obtain a 99.7 percent confidence level in a p-chart, we would use a value of 3 for "z". - ANS True
Acceptance sampling is performed on goods that already exist to determine what percentage of items
conforms to specifications - ANS True
In acceptance sampling, the number of units in the sample (n) is determined by the interaction of the
acceptable quality level (AQL), the lot tolerance percent defective (LTPD), the probability of rejecting a
high-quality lot (alpha), and the probability of accepting a low-quality lot (beta). - ANS True
,In acceptance sampling, the value for the acceptance number (c) is determined by the interaction of the
acceptable quality level (AQL), the lot tolerance percent defective (LTPD), the probability of rejecting a
high-quality lot (alpha), and the probability of accepting a low-quality lot (beta). - ANS True
AQL stands for accepting questionable lots in production quality management - ANS False
LTPD in acceptance sampling stands for lot tolerance for parts defective. - ANS False
The Greek letter alpha is associated with consumer's risk - ANS False
The probability associated with rejecting a high-quality lot is denoted in acceptance sampling with the
Greek letter alpha. - ANS True
The probability associated with accepting a low-quality lot is denoted in acceptance sampling with the
Greek letter alpha. - ANS False
The producer's risk associated with rejecting a high-quality lot is denoted in acceptance sampling with
the Greek letter beta - ANS False
Total, 100 percent inspection can never be cost justified - ANS False
One hundred percent inspection is justified when the cost of inspection is low. - ANS False
Sampling plans are generally displayed graphically through the use of operating characteristic (OC)
curves. - ANS True
, The capability index (Cpk) calculates the percentage of items being produced within specifications - ANS
False
The capability index (Cpk) indicates the position of the mean and tails of a process's variance relative to
design specifications - ANS True
Standard practice in statistical process control for variables is to set control limits so that 95 percent of
the sample means will fall within the UCL and the LCL. - ANS False
In variables sampling, the actual measurements of the variable observed are used regardless of whether
the unit is good or bad. - ANS True
In monitoring process quality, we might use which of the following statistics?
A. Absolute values
B. Percentage deviation from tolerance centers
C. "k" values for the sample mean
D. Logarithmic control intervals
E. Difference between the highest and lowest value in a sample - ANS E
You have just used the capability index (Cpk) formulas to compute the two values "min [2, 2.5]." Which
of the following is the proper interpretation of these numbers?
PASSED
Variation in production systems that is caused by factors that can be clearly identified and possibly even
managed is called assignable variation. - ANS True
An example of assignable variation in a production system may be that workers are not identically
trained - ANS True
An example of assignable variation in a production system may be that a machine is not adjusted
properly - ANS True
Variation that is inherent in a production process itself is called assignable variation. - ANS False
Variation that is inherent in a production process itself is called common variation. - ANS True
It is impossible to have zero variability in production processes. - ANS True
Genichi Taguchi's view of the cost of quality is that variance is a discontinuous function - ANS False
The capability index is used to gauge economic changes in service systems. - ANS False
Process control is concerned with monitoring quality after the product or service has been produced. -
ANS False
Statistical process control involves testing random samples of output from a process to determine
whether the process is producing items within a preselected range. - ANS True
,Measurement by attributes means taking a sample, measuring the attribute in question, and
determining the level of quality in the population from which the sample was drawn. - ANS False
Attributes are those quality characteristics that are classified as either conforming or not conforming to
specification - ANS True
A p-chart has upper and lower control limits expressed as lines on the chart. As long as the sample
values fall between these two lines, there is no need to investigate process behavior - ANS False
The p-chart is only useful for sampling that deals with continuous variables. - ANS False
The value for "z" used in quality control charts is based on the degree of confidence you want to have in
the resulting UCL and LCL values. - ANS True
If the fraction defective is 0.12 based on a sample size of 16, the standard deviation used in the p-chart
is about 0.08. - ANS True
If the fraction defective is 0.4 based on a sample size of 100, the standard deviation used in the p-chart
is about 0.10. - ANS False
To obtain a 99.7 percent confidence level in a p-chart, we would use a value of 3 for "z". - ANS True
Acceptance sampling is performed on goods that already exist to determine what percentage of items
conforms to specifications - ANS True
In acceptance sampling, the number of units in the sample (n) is determined by the interaction of the
acceptable quality level (AQL), the lot tolerance percent defective (LTPD), the probability of rejecting a
high-quality lot (alpha), and the probability of accepting a low-quality lot (beta). - ANS True
,In acceptance sampling, the value for the acceptance number (c) is determined by the interaction of the
acceptable quality level (AQL), the lot tolerance percent defective (LTPD), the probability of rejecting a
high-quality lot (alpha), and the probability of accepting a low-quality lot (beta). - ANS True
AQL stands for accepting questionable lots in production quality management - ANS False
LTPD in acceptance sampling stands for lot tolerance for parts defective. - ANS False
The Greek letter alpha is associated with consumer's risk - ANS False
The probability associated with rejecting a high-quality lot is denoted in acceptance sampling with the
Greek letter alpha. - ANS True
The probability associated with accepting a low-quality lot is denoted in acceptance sampling with the
Greek letter alpha. - ANS False
The producer's risk associated with rejecting a high-quality lot is denoted in acceptance sampling with
the Greek letter beta - ANS False
Total, 100 percent inspection can never be cost justified - ANS False
One hundred percent inspection is justified when the cost of inspection is low. - ANS False
Sampling plans are generally displayed graphically through the use of operating characteristic (OC)
curves. - ANS True
, The capability index (Cpk) calculates the percentage of items being produced within specifications - ANS
False
The capability index (Cpk) indicates the position of the mean and tails of a process's variance relative to
design specifications - ANS True
Standard practice in statistical process control for variables is to set control limits so that 95 percent of
the sample means will fall within the UCL and the LCL. - ANS False
In variables sampling, the actual measurements of the variable observed are used regardless of whether
the unit is good or bad. - ANS True
In monitoring process quality, we might use which of the following statistics?
A. Absolute values
B. Percentage deviation from tolerance centers
C. "k" values for the sample mean
D. Logarithmic control intervals
E. Difference between the highest and lowest value in a sample - ANS E
You have just used the capability index (Cpk) formulas to compute the two values "min [2, 2.5]." Which
of the following is the proper interpretation of these numbers?
