Hi,
I have data that consists of groups of subgroups. Each subgroup consists of one value. When I run the process screening on it, I get an overall sigma (the sigma between the different subgroups) and a within sigma. I cannot figure out what this within sigma is. I would like to use the stability index in my analysis, but cannot figure out how it (or the stability ratio) is calculated. Where does this within sigma come from/how is it calculated?
For some reason i can not upload the process screening or the data table. I have them availableif they are necessary for answering my question.
Thanks,
Tova
Minimum subgroup size is two. If you run.
names default to here(1);<BR />dt = open("$SAMPLE_DATA\Consumer Prices.jmp");
dt << Process Screening(
Y( :Price ),
Grouping( :Series ),
Control Chart Type( "Indiv and MR" ),
Time( :Date ),
Subgroup Sample Size( 1 )// this can't happen
);
You should get a warning in log saying
Minimum subgroup size is 2.
If you do this via the GUI then it should actually give you a popup.
If you take your process screening and save to script window I'm guessing it overwrote your Subgroup Sample Size( 1 ) with a 2.
Even if you give it a subgroup column, it should do this.
