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Should Observations Be Grouped for Effective Process Monitoring? (PDF, 1.70 MB)
When control chart combinations are based on samples of n>1 and taking a concentrated sample is a feasible option, concentrated sampling is better than dispersed sampling for detecting sustained shifts in the process mean or standard deviation.

Statistics Roundtable: n (PDF, 216 KB)
A manufacturer suspects that onions may have been added accidentally to cans of tomato sauce. How many cans must be checked to find out if it's true? And how many samples are needed to find out how much onion ended up in each can?

Developing Control Charts and Illustrating Type I and Type II Errors (PDF format, 90 KB)
A class exercise illustrates the development of control charts and the two types of errors that can be made; sample data drawn from a sampling bowl in an in-class simulation are used.

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