p chart question

[Former Member]

Hello,

1) Is it required to specify (a static value) for the SampleSize parameter (Default size - 100) for an attribute chart? or could this value be specified through a query?

2) Could someone provide some illustrative (sample data) for plotting a "p" chart in MII (the fraction of all defective units per total units in the sample).

Appreciate any ideas

Thanks.

[Former Member]

Spend some time reading and learning here:

http://www.statsoft.com/textbook/stathome.html

It is an excellent resource on the theory and practice of statistical analysis for manufacturing and other applications.

And best of all, it is online and free!

[Former Member]

Thanks Rick. This link is indeed very exhaustive and useful.

How do I specify a variable sample size in MII

Appreciate your help again !

[Former Member]

If I remember correctly, the variable sample size needs to be returned as part of the query results

[Former Member]

Rick,

A related question in the P-chart-

As you suggested, we specified a Column from our query results for the "Sample size Column" for the P-chart.

This worked and the P-chart was plotted. The points and the Centerline (P) are displayed correctly as expected. However the Control limit lines (UCL, LCL) are not getting displayed !!

I was also suprised to note that these limits (LCL, UCL, CL) are actually getting calculated (when I rightclick -> Data --> SPCResults --->Upper Chart Data Points, they show here).

However these are not calculated (and shown as 'NA'??) when I right click -> Data --> Summary Statistics.

I have enabled the "Calculate Control Limits" and :Show Upper Control Limits"

Am I missing something?

Appreciate any ideas.. Thanks!