Chapter 10: Smartbook

If the number of standard deviations is not specified when computing control charts, what is an appropriate default value? +/- 4 standard deviations +/- 1 standard deviation +/- 2 standard deviations

+/- 2 standard deviations

Which of the following statements about inspection frequency are is/are correct? -The goal of inspection is to maximize the cost of passing defectives and performing inspection. -A stable process will require less frequent checks than an unstable process. -Operations with a high ratio of human-to-machine labor require less inspection. -The more lots being produced the more inspections are needed.

-A stable process will require less frequent checks than an unstable process. -The more lots being produced the more inspections are needed.

Select all the ways quality assurance can be part of an organization's operations strategy. -Adopt continuous process improvement methods to increase customer satisfaction with product quality. -Improve process capability to reduce need for inspection -Perform run tests before each process sampling to ensure non-random variation is present. -Only upgrade product and service design when the competition makes an improvement.

-Adopt continuous process improvement methods to increase customer satisfaction with product quality. -Improve process capability to reduce need for inspection

When is the nonrandom variation shown on a control chart a positive outcome? -An observation above the upper control limit on a R-chart. -An observation below the lower control limit on a R-chart. -An observation below the lower control limit on a c-chart. -An observation below the lower control limit on a p-chart. -An observation above the upper control limit on a p-chart. -An observation above the upper control limit on a c-chart.

-An observation below the lower control limit on a R-chart. -An observation below the lower control limit on a c-chart. -An observation below the lower control limit on a p-chart.

Though process improvement initiatives come with a cost, benefits of more capable processes may outweigh and can include which of the following? -Fewer service complaints -Lower warranty costs -Lower productivity -Less need for inspection

-Fewer service complaints -Lower warranty costs -Less need for inspection

What are the different inspection points in manufacturing? (Select all correct answers.) -Finished goods after production -Half-way point of production (~50% complete) -Before a costly, irreversible or covering operation/process. -Raw materials & purchased parts before production

-Finished goods after production -Before a costly, irreversible or covering operation/process. -Raw materials & purchased parts before production

Managers must make a number of important decisions about the use of control charts. What are they? -How often samples should be taken -At what points in the process to use control charts -What type of control chart to use -How many control charts to use to monitor the process -What size samples to take -What tools to use to take measurements

-How often samples should be taken -At what points in the process to use control charts -What type of control chart to use -What size samples to take

What are some risks of using capability indexes? -If the process is not centered but Cp is used anyway, it gives misleading indications. -If the process output is not normally distributed, statistical inferences are incorrect. -If the process stability is checked too often, it gives conflicting signals. -If the process is not stable, Cp and Cpk are meaningless.

-If the process is not centered but Cp is used anyway, it gives misleading indications. -If the process output is not normally distributed, statistical inferences are incorrect. -If the process is not stable, Cp and Cpk are meaningless.

Which of the following statements is/are correct about Inspection? -Only lots with zero percent defects can pass inspection. -Lean organizations tend to rely heavily on inspection. -Inspection involves checking for conformance against a quality standard. -Inspection can occur before, during or after production.

-Inspection involves checking for conformance against a quality standard. -Inspection can occur before, during or after production.

Which is/are examples of acceptance sampling? -Inspection of final assembly lots after production -Inspection of product at intermediate stage of production -Inspection of raw material batches before production

-Inspection of final assembly lots after production -Inspection of raw material batches before production

Which of the following are examples of inspection points in service organizations? Kitchen cleanliness at fast food restaurant at shift start Process monitoring at the production department of a manufacturing company Outgoing patient billing accuracy at medical clinic Equipment safety checks at coal mining facility at beginning of the day

-Kitchen cleanliness at fast food restaurant at shift start -Outgoing patient billing accuracy at medical clinic

Under which conditions would on-site inspection be better than off-site at a specialized test lab? -Need for quick inspection results due to delivery schedule -Organization does not wish workers to influence inspections -Alteration or contamination of samples during transfer to lab

-Need for quick inspection results due to delivery schedule -Alteration or contamination of samples during transfer to lab

What are some ways operations managers can improve process capability? -Reduce the process variability -Standardize process steps -Inspect all incoming raw material -Upgrade or automate equipment

-Reduce the process variability -Standardize process steps -Upgrade or automate equipment

Which of the following statements is/are correct about Specifications? -Specifications are tolerances established by Engineering and/or the Customer. -Specifications are a range of values in which all units of output must fall to be acceptable. -Specifications are statistical limits in which all samples must fall for the process to be in control.

-Specifications are tolerances established by Engineering and/or the Customer. -Specifications are a range of values in which all units of output must fall to be acceptable.

Which of the following elements are part of the calculation for the capability analysis statistic Cpk? -Take the smaller of the two calculation values for Cpk. -If a process is not centered it is not going to be capable. -Calculate the distance from the mean to the upper tolerance then do the same to the lower. -Use the ratio: Specification width / Process Width to 6σ

-Take the smaller of the two calculation values for Cpk. -Calculate the distance from the mean to the upper tolerance then do the same to the lower.

Run tests can reveal non-random patterns in time-ordered data. Select three patterns that might be seen. -Trend -Cycles -Bias -Scatter Plot -Points outside limits

-Trend -Cycles -Bias

The implication for Taguchi is that reducing the variation inherent in a process will result ______. -making poor quality unacceptable to society -lowering the cost of poor quality -lowering the loss to society -increasing the cost of poor quality

-lowering the cost of poor quality -lowering the loss to society

A six sigma process will have a process capability index equal to: 1.00 2.00 6.00 1.33

2.00

Select the best definition of Quality Control. -A process that samples all raw inputs before production and rejects non-conformances back to the supplier. -A process using a statistical method to detect when a process is slipping out of control. -A process that measures output relative to a standard and takes action when discrepancies occur.

A process that measures output relative to a standard and takes action when discrepancies occur.

Select the best definition of a "run." -When data is within the control limits -The period of time when an inspector is taking samples -A sequence of observations with a certain characteristic

A sequence of observations with a certain characteristic

Select the best definition of a control chart. -Scatter plot data graph developed by Deming for statistical manufacturing control. -A time-ordered plot of sample statistics used to determine randomness or non-randomness. -A normal distribution of sample means collected over time.

A time-ordered plot of sample statistics used to determine randomness or non-randomness.

What is the rationale and basis for statistical process control? -Acceptable variation within probability limits -Last month's quality metrics on process stability and how current month changed -Six sigma calculations and alpha error score Results of previous corrective actions on the existing process

Acceptable variation within probability limits

What characteristic is measured in a run test? -Up/down -Anything observable -Above/below median

Anything observable

What is the best synonym for inspection from the below list? -Opinion -Measurement -Appraisal -Rejection

Appraisal

When +/- 2 standard deviation control limits are used in a process control chart, which of the below statements are true? -Approximately 68% of the time random data points will fall within (inside) the upper and lower control limits. -Approximately 95.5% of the time random data points will fall within (inside) the upper and lower control limits. -99.7% of the time random data points will fall beyond (outside) the upper and lower control limits.

Approximately 95.5% of the time random data points will fall within (inside) the upper and lower control limits.

What happens when a process is not stable? -Capability index will be smaller -The process will not be centered -Capability index is meaningless

Capability index is meaningless

When the results of quality control are unacceptable, what is the next step? -Finding a new supplier -Corrective action -Selecting additional samples

Corrective action

What is the formula for Cp? -Cp = Process Width / Specification Width -Cp = 6 standard deviations / Upper - Lower specification -Cp = Specification Width / Process Width

Cp = Specification Width / Process Width

Which scenario would indicate the need for off-site testing at a centralized testing facility? -Customer specifications for satellite component require dust-free, no vibration test -Automobile manufacturing company practices "Quality at the Source" as part of Total Quality Management program -Shipbuilding company orders inspectors to check for hull cracks after welding operations

Customer specifications for satellite component require dust-free, no vibration test

What is the first step in the control process? -Measure the characteristics that are going to be controlled. -Identify a standard of comparison for evaluating measurements. -Define in sufficient detail what is to be controlled.

Define in sufficient detail what is to be controlled.

Which of the following is the best definition of statistical process control? -It is quality assurance that relies primarily on inspection of lots (batches) of previously produced items -It is analysis of data from some point in the process to determine if the process is likely to be in or out of control. -It uses statistical calculations during finished product lot inspection as basis for rejection of defectives.

It is analysis of data from some point in the process to determine if the process is likely to be in or out of control.

What are the two different types of run tests? -Median and Up/Down -Trend and Bias -C-chart and P-chart -Mean and Range

Median and Up/Down

When points fall within the control limits

Random variation is suggested and the process is probably in control.

How do Specifications differ from Control Limits? -Specifications refer to the entire process and control limits are set on the sampling distribution. -Specifications are measurements and control limits are used for attribute data. -They do not differ; specifications and control limits are theoretically the same ranges.

Specifications refer to the entire process and control limits are set on the sampling distribution.

How does Taguchi's belief about quality differ from the traditional view? -As long as output is within specifications, there is no cost. -Companies which use his methodologies have higher costs to obtain good quality. -The cost of poor quality increases as the output approaches the specification limit.

The cost of poor quality increases as the output approaches the specification limit.

In a control chart when a data point falls outside the control limits (upper and lower), what must be concluded? -Due to random chance data points will routinely fall outside the control limits. -The process appears non-random and should be checked. -More than one data point must be beyond the limits before halting the process.

The process appears non-random and should be checked.

Which of the following exemplify a capable process? -The range of process variability is much less than the width of customer specifications. -The range of process variability is exactly equal to the width of customer specifications. -The range of process variability is much greater than the width of customer specifications.

The range of process variability is much less than the width of customer specifications.

Comparing a theoretical sampling distribution to the process distribution, which of the following is true? -The sampling distribution will not be normal if the process distribution is not normal. -Their means are slightly offset. -The variability of the sampling distribution is less than that of the process distribution

The variability of the sampling distribution is less than that of the process distribution.

When comparing a sampling to a process distribution, what are the most important things to note? -They have different means, are normally distributed, and sampling has greater variability. -They have the same means, are normally distributed, and sampling has less variability. -The distribution graphs for each are essentially identical and interchangeable.

They have the same means, are normally distributed, and sampling has less variability.

Why do statistical process control analysts perform run tests, even when control charts demonstrate all points within the limits? -To determine whether patterns can be detected. -The control charts suggested the process was out of control. -The sample sizes may not be large enough to detect non-randomness.

To determine whether patterns can be detected.

Select the best definition of capability analysis. -To set up control limits and take sample averages to determine if a process is in control. -To track the tool calibration used in product manufacturing for uneven wear, replacement, etc. -To determine whether the variability of a stable process falls within tolerances.

To determine whether the variability of a stable process falls within tolerances.

When is the capability analysis statistic Cp used? -When there is non-random variability detected in the process. -When a process is centered between the upper and lower specifications. -When the process is not centered between the upper and lower specifications. -When the process is found to be unstable and out of control.

When a process is centered between the upper and lower specifications.

When is the capability analysis statistic Cpk used, instead of Cp? -When a process is not centered between the upper and lower tolerances. -When a process is centered between the upper and lower tolerances. -When a process produces samples outside the control limits.

When a process is not centered between the upper and lower tolerances.

In order to create new samples, the runs are transformed into a series of Us and Ds and into a series of As and Bs. True false

false

A mean control chart is used to check ______. -for central tendency of a variable -whether a process is too highly dispersed -if the sampling distribution is not normal

for central tendency of a variable

There is too much inspection when the cost of inspection is __________ the cost of passing defectives. equal to less than greater than

greater than

The decision about where to use control charts should focus on aspects of the process that _______. -are visible to the customer, and can be automated -have the lowest cost of inspection, and require the least time to collect samples -have a tendency to go out of control, and affect product or service characteristics

have a tendency to go out of control, and affect product or service characteristics

Given a stable process, we must ask the question whether the ______ of process output is within an acceptable range. conformance inherent variability non-random variability

inherent variability

Statistical process control is ______. -quality control efforts that occur during production -performed on lots of previously produced items -inspection of raw materials, components or sub-assemblies from suppliers

quality control efforts that occur during production

Six Sigma refers to achieving a process variability so small that the design specifications represent ___ standard deviations above and below the process mean. two three six

six

six sigma quality

small variation

Random variation in a process indicates __________; whereas non-random variation indicates process __________. -stability/instability -non-defects/defects -conformance/non-conformance

stability/instability

A range control chart is used to check ______. -the central tendency of a process -the dispersion of a variable -whether attribute data has been counted

the dispersion of a variable

For attribute data a c-chart is used to monitor ______. -the number of defects per unit -the random count of product in each sample -the fraction of defective product in a given sample

the number of defects per unit

For attribute data a p-chart is used to monitor ______. -the proportion of defective items generated by a process -the defect count in a sampled product -the percentage of time a process goes out of control

the proportion of defective items generated by a process

In the control process, only those characteristics that can be counted or measured are candidates for control. True false

true

Sometimes non-random variation can indicate excellent quality. True false

true