October 2001

Vol. 3, No. 10

Quality Quiz

Here's October's question from Professor Cleary. After you have read the question, click on the response that you think is correct. If you answer correctly, you can register to win a free copy of Quality Gamebox.

Cal Q. Lashon is a quality manager for Stop & Go, a brake shoe manufacturer that has secured a long-term contract to supply its product to a major automotive manufacturer. Cal was a former math teacher in a rural high school, and was hired by S & G not only because of his prowess with numbers, but for his ability to instruct his staff about statistical concepts. One of the members of his team, Melba Toste, has been asked to pursue capability analysis of length, one dimension of the brake shoes that the company makes.

Melba uses a control chart to determine that the process is in control. She also knows that the data must follow a normal distribution before capability can be addressed. Using CHARTrunner, Melba creates a histogram of brake shoe length, and notices that the data follows a normal distribution.

Cal stops by to look at Melba's charts, and--always looking for a teachable moment--asks what the coefficient of variation is for the process. Although Melba has no idea what the term means, she does not want to give her boss any indication that she might be incapable of pursuing capability analysis, so she mumbles, "This is a critical indicator of the compatibility of all elements in the process."

Is she correct? Select from the following the response that best indicates what the coefficient of variation measures or describes:

A)  the capability of a process;

B) whether a process is in or out of control;

C)  the ratio of a mean to a standard deviation in a data set;

D) the peakedness of a distribution.

Click on the correct answer, and link to the solution.

Copyright 2001 PQ Systems.

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