July 2001

Vol. 3, No. 7

Quality Quiz from Dr. Cleary

You're right!

Unfortunately, although Rosa Mongthorns' decision is not based on deception as was last month's action, it is founded in ignorance.

When spec limits are one-sided--that is, the lower spec limit is not set, as in this case--no number should be substituted for the missing spec. "Zero" does not mean, after all, "never mind," but designates a specific value of sorts.

To learn more about one-sided spec limits, go to http://web1.pqsystems.com/cpk-with-one-spec.htm for an expanded discussion provided by Matthew Savage, SPC projects manager and technical support guru for PQ Systems. 

Copyright 2001 PQ Systems.

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