Vol. 8, No. 5

May 2006

PQ Systems

New GAGEpack EZ release

Quality Quiz: With a video!

Six Sigma

Data in everyday life

Bytes and pieces

FYI: Current releases


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Quality Quiz:

Click here for a more complete video explanation

Paint manufacturer Color in a Can, with its evasive quality manager, Walker Runn, is about to discover the pot of SPC at the end of its rainbow.

Walker Runn, caught in a significant statistical error, was put on the sidelines, so to speak. His instructions were to take some time to learn a little more about statistical process control, and the perfect teacher was none other than Dan Druff, the vice president who uncovered Walker's incompetence in the first place. Dan Druff is himself a highly skilled statistician, though he's known to be a little flaky, and Walker has been following him around to learn enough to keep his job.

After several months of this apprenticeship, Dan has given Walker a chance to demonstrate what he’s learned by producing an analysis of variance (ANOVA) based on the output of three Color in a Can plants.

The data related to his output is as follows:

"Aha," Walker says, realizing that even without full understanding, he can simply enter the data into an easy-to-use software program, DOEpack EZ, for the calculations, then slip it into a PowerPoint presentation he is preparing for Dan Druff's review.

Dan goes over the ANOVA analysis, reviewing for Walker what he had learned from his disastrous hypothesis testing assumptions last month. He wants to be sure that Walker understand hypothesis testing as well as ANOVA, so he begins to question him about the F value of 4.114 that is indicated on the ANOVA output.

"F" stands for 'facilities,'" Walker asserts confidently, sure that the chart is self-explanatory and bears no deep statistical secrets. Color in a Can has three facilities, or F's, he continues. It's clear that this can't be the correct response, and no doubt Walker Runn better walk or run to the nearest employment agency after this debacle. But can you define F value? Pick the correct response from the two given:

a) F value refers to the ratio of variation between samples to the variation within samples.

b) F value refers to the spread in the control limits for the data that is provided.

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