Quality Quiz from Professor Cleary

Congratulations:
"B" is the correct answer!

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In fact, this process is out of control. What the dynamic duo failed to take into account is the fact that the 's in a process that is in control will form a normal distribution, as below.

Viewing the area under a normal curve and moving plus and minus one standard error will capture about 64 percent of the data; plus or minus two standard errors, 95 percent; and plus or minus three standard errors, 99.7 percent.

Returning to the chart produced by Phillip D. Tank, one can see that 100 percent of the X-bars ('s) are within plus and minus one standard error. This may appear to be positive, but in fact it is statistically impossible to achieve.

It may be that Phillip has deliberately altered the data or tampered with the process itself. This is known as the "too good to be true" outcome. It may be that in his earnest effort to unseat Marsha and Maura, he has used a magic pencil to record data.

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