Exam 7: Statistical Process Control

Repeated sampling of a certain process shows the average of all sample ranges to be 1.0 cm. The sample size has been constant at n = 5. What are the 3-sigma control limits for this R-chart?

__________ is variation in a production process that can be traced to specific causes.

The usual purpose of an R-chart is to signal whether there has been a

What is the difference between natural and assignable causes of variation?

In acceptance sampling, a manager can reach the wrong conclusion if the sample is not representative of the population it was drawn from.

A Cpk index of 1.00 equates to a defect rate of

The process capability measures Cp and Cpk differ because

What do the terms producer's risk and consumer's risk mean?

The c-chart signals whether there has been a

If the process average is in control, then the process range must also be in control.

A hospital-billing auditor has been inspecting patient bills. While almost all bills contain some errors, the auditor is looking now for large errors (errors in excess of $250). Among the last 100 bills inspected, the defect rate has been 16%. Calculate the upper and lower limits for the billing process for 99.7% confidence.

Average outgoing quality (AOQ) usually

The specifications for a manifold gasket that installs between two engine parts calls for a thickness of 2.500 mm ± .020 mm. The standard deviation of the process is estimated to be 0.004 mm. What are the upper and lower specification limits for this product? The process is currently operating at a mean thickness of 2.50 mm. (a) What is the Cp for this process? (b) The purchaser of these parts requires a capability index of 1.50. Is this process capable? Is this process good enough for the supplier? (c) If the process mean were to drift from its setting of 2.500 mm to a new mean of 2.497, would the process still be good enough for the supplier's needs?

Acceptance sampling accepts or rejects an entire lot based on the information contained in the sample.

The higher the process capability ratio, the greater the likelihood that process will be within design specifications.

Consumer's risk is the probability of

Acceptance sampling's primary purpose is to

The specification for a plastic liner for concrete highway projects calls for a thickness of 6.0 mm ± 0.1 mm. The standard deviation of the process is estimated to be 0.02 mm. What are the upper and lower specification limits for this product? The process is known to operate at a mean thickness of 6.03 mm. What is the Cp and Cpk for this process? About what percent of all units of this liner will meet specifications?

The mean and standard deviation for a process for which we have a substantial history are ? µ = 120 and σ = 2. For the x-bar chart, a sample size of 16 will be used. What is the mean of the sampling distribution?

The __________ is a quality control chart that indicates when changes occur in the central tendency of a production process.