Chapter 10: Quality Control

Select all that apply Which of the following statements about Type I error is/are correct?

- A Type I error is concluding non-randomness and being mistaken. - A Type I error's alpha risk equals the probability (area) in the two "tails."

Select all that apply Which of the following statements is/are correct about Inspection?

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

Select all that apply Which is/are examples of acceptance sampling?

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

Select all that apply Which of the following are measured using attributes?

- Number of calls in a day - Number of defects

Select all that apply Which of the following are examples of inspection points in service organizations?

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

Select all that apply What are the different inspection points in manufacturing?

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

Select all that apply Which of the following statements is/are correct about the sampling distribution?

- Sampling distribution is narrower than the process distribution. - Sampling distribution is a plot of many sample means.

Select all that apply 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.

Select all that apply Which of the following statements about inspection frequency are is/are correct?

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

Select all that apply What are the basic issues of quality control inspection?

- Whether to inspect attributes or variables - Where inspection should take place - How much and how often to inspect - At what stage of the process inspection should occur

True or false: In acceptance sampling, a type of quality control inspection, 100% of product in a given lot are checked for conformance.

False

Which of the following is the best definition of statistical process control?

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.

Inspection during transformation is called what?

Process control

When a sample average falls inside the control limits, what can be concluded about the process?

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

Select the best definition of assignable variation.

Special, non-random variation traceable to a definite cause.

How do Specifications differ from Control Limits?

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

Select the best definition of process variability.

The natural or inherent variability in a process.

In a control chart when a data point falls outside the control limits (upper and lower), what must be concluded?

The process appears non-random and should be checked.

Select the best definition of Quality Control.

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

Select the best definition of a control chart.

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

A Type I Error is referred to by what other name?

Alpha Risk

What is the best synonym for inspection from the below list?

Appraisal

When +/- 2 standard deviation control limits are used in a process control chart, which of the below statements are true?

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

Select the best definition of random variation.

Common variation inherent in a process occurring by chance.

When the results of quality control are unacceptable, what is the next step?

Corrective action

When comparing a sampling to a process distribution, what are the most important things to note?

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

True or false: All processes have variation.

True

What is the difference between variable and attribute data?

Variable data is measured on a continuous scale and attribute data is counted using discrete numbers.

There is too much inspection when the cost of inspection is __________ the cost of passing defectives.

greater than

Given a stable process, we must ask the question whether the ______ of process output is within an acceptable range.

inherent variability

Statistical process control is ______.

quality control efforts that occur during production

Random variation in a process indicates __________; whereas non-random variation indicates process __________.

stability/instability

One basic issue of inspection is what type of data to collect. If we can measure the value of a characteristic, we are collecting ______ data.

variable