Some industries use "six sigma" control to establishing upper and lower control limits

Submitted by aliweb on Tue, 08/21/2012 - 18:14

Q. Some industries use "six sigma" control to establishing upper and lower control limits (UCL and LCL) to provide very tight process control. ("Sigma" is the standard deviation of the probability distribution.) The more traditional limits for process control charts are as follows:

a. Two sigma between UCL and LCL 

b. Six sigma between UCL and LCL

c. Three sigma between UCL and LCL

d. Three sigma between specification limits (UCL and LCL)

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PMP / CAPM exam Question bank
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sspawar

Wed, 08/22/2012 - 07:51

ans would be C

MichelleNagel

Wed, 08/22/2012 - 10:40

I destroyed the exam, I mean really destroyed it.
Few key points and tools I can suggest. I am going to write this on the other forum.

aliweb

Wed, 08/22/2012 - 11:50

You stole my words :@

I was planning on using these words to write my LL when I pass the exam :(

aliweb

Wed, 08/22/2012 - 11:52

That's what I also thought but the correct answer is B.

The question is from Farndale 262 questions and I think the answer given by them is wrong that's why I posted here to get people input. Because control charts clearly say the range is +- 3 sigma.

Correct answer should be C.

sspawar

Wed, 08/22/2012 - 17:49

See +/- 3  sigma is a traditional range or limit values, may be applicable to certain processes, it is not any universal scale or standarized value.

PMBOK is using word generally or usually , means it is not a rule for all.

PMBOK figure no 8.5 and 8.6 of control chart are not showing any 3 sigma limits.

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Generally framing question on 3sigma as a control chart limit - is wrong tradition, and should be stopped and deleted . Such question in Lahman series is also there. I advised to ignore totally such questions.

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