Hi,
I'm looking for a published example (online or in the docs) of data and results from running an S chart (i.e. control chart for within group standard deviations), where the group size varies.
I see an example of this for an XRChart:
http://support.sas.com/documentation/onlinedoc/qc/ex_code/141/shwmns.html
But I want an SChart (or XSCHART), using the default method used by SAS (ASTM 1976).
Goal is to find some published data to use in a validation report. Would appreciate any suggestions. (I'm going to try and buy the ASTM book, but hoping to find something online faster than snail mail).
Thanks,
--Q.
Not sure what "ASTM 1976" means, but have you seen the chapter "Analyzing Quality Data with SAS", which includes an XSCHART example on p 9?
The excerpt is from Rutledge Just enough SAS: A Quick-Start Guide to SAS for Engineers. The data are available from the book web page.. Just click "Example Code and Data."
Thanks Rick, I hadn't seen that book.
Unfortunately, I'm looking for an example of an S chart (or XSCHART) where the subgroup size varies, so the process limits on the S chart will also vary accordingly.
For example, this:
data have; do lot=1 to 20; do n=1 to floor(ranuni(3)*20); *random number of values in each group; y=100+sqrt(10)*rannor(3); output; end; end; run; proc shewhart data=have; xschart y*lot; run;
Produces a chart like:
By "ASTM 1976" was referring to the reference for the calculation in th docs:
American Society for Testing and Materials (1976), ASTM Manual on Presentation of Data and
Control Chart Analysis, 1916 Race Street, Philadelphia, PA 19103.
Amazon is selling it for $5, so hopefully I'll be lucky when it arrives. : )
If you go to Google and search in "Images" for
shewhart x chart unequal sample size
you will see many examples. I'm not sure whether these qualify as "published examples."
For example, one instance is a set of course notes:
http://www.math.montana.edu/jobo/st528/documents/chap6b.pdf (p 68-69)
If you need a published example of high importance, you can find example data and chart on pp 244-248 of
Introduction to Statistical Quality Control by Douglas C. Montgomery, 4th Ed.
Do the results have to be created by SAS?
Are you ready for the spotlight? We're accepting content ideas for SAS Innovate 2025 to be held May 6-9 in Orlando, FL. The call is open until September 25. Read more here about why you should contribute and what is in it for you!
ANOVA, or Analysis Of Variance, is used to compare the averages or means of two or more populations to better understand how they differ. Watch this tutorial for more.
Find more tutorials on the SAS Users YouTube channel.