This question has to do with the P chart. If possible I need to have a
response by March 18.  Here's the question:
Nuts and bolts are made in a two shift operation.  Management would
like to know if there is any difference in the proportion of
defectives produced by these two shifts.  Management suspect that the
second shift has a higher rate of defectives, since the workforce is
not highly trained and supervision may be lacking.  How would one use
the p control chart to determine if there is a difference between the
two shifts?

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Request for Question Clarification by tutuzdad-ga on 17 Mar 2004 07:12 PST

I can tell you where you can purchase sofware that will do what you
are asking eliminating much of the work, calculation, human error and
effort. The software is $199.00 for single user license but there is
also a FREE demo version that you can download to try. I have little
doubt that the software will provide you with the chart you are hoping
to create but it's possible that the free demo "may" do the trick for
you.

Would you like this as an answer?

Regards;
tutuzdad-ga

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Request for Question Clarification by tutuzdad-ga on 17 Mar 2004 07:17 PST

Further, to add to the software's reputation, it is currently being
used by 3M, Boeing, Chevron, Hewlet Packard, Kraft Foods and Lockheed
just to name a few of the several hundred companies and universities
listed by the manufacturer.

Regards;
tutuzdad-ga

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Clarification of Question by dana3-ga on 17 Mar 2004 08:48 PST

Thanks, but that is not the answer I was looking for. I guess I was
looking more for an explaination of the P control chart patterns and
possible causes that would determine the differences between the two
shifts.  Is there a website I can go to that would give me more
information on how to use control charts like the P chart with a good
definition?

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Request for Question Clarification by tutuzdad-ga on 18 Mar 2004 11:30 PST

I don't know of one personally. Hopefully someone else can locate one for you.

regards;
tutuzdad-ga

Hi,

I think dana3 is talking about the p chart used in statistical process control.

To create the P chart the Upper Warning Limits and Upper Action Limits
need to be calculated from the samples from the more successful shift.
 The data from the samples from the less successful shift should then
be plotted using the limits calculated.

From what you say, it does seem that the operators are at fault as the
machinery will remain the same regardless of the shift.

If I can help further let me know.

simonf

My previous comment assumes a constant sample size and is used with an np-chart.

Thanks for the last comment, it was more in-line with what I was
looking for.  I was able to develop a response to my question by
reading several books by authors who specialize in Quality Control
Management.

A good book that I have used in the past is Statistical Process
Control by John S Oakland. The ISBN is 0-7506-5766-9.

Thanks for the title to the reference book, you have been very helpful!