Hi Brian -

I am familiar with the terms UCL and LCL. Do you know the formula StatPlus uses to
calculate these control limits? For many purposes, ± 3 SD is used. For other
applications, for example, design allowables for aerospace materials, the
relationship is more complex, based on confidence limits which are close to ± 3 SD
for a typical number of observations, but may be wider or narrower depending on the
actual number of observations in the data base from which they are derived. Blah blah.

The point is, if you know the limits, you can add the lines.

- Jon
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Jon Peltier, Microsoft Excel MVP
Peltier Technical Services
Tutorials and Custom Solutions
http://PeltierTech.com/
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Brian Sells wrote:

Jon,
Thanks for that page... I am going to try the stuff in it and see if it is
what I need. The lines I'm refering to are the Upper Control Limit(UCL),
Lower Control Limit(LCU)
and the center line is basically an average line. These lines are
automatically put in the chart by the StatPlus add-in I have for excel. These
are process control charts and when you create them there is no option for
creating them dynamically. With John's page I was able to get the xbar and
moving range charts to become dynamic but I lost the lines. They are a
critical part of the chart and the values that are computed for them is the
precise reason I need them in there. The UCL and LCL are the limits, positive
or negative, that I need for the spreadsheet. Basically it is all statistical
monitoring but I need them for what I am creating. I will definitely try the
methods from your site before I go any farther and let you know if it does
what I need it to do. Thanks for the assistance.
Regards,
Brian Sells