Edustrial, a great tool/software and learning site(s) are found at:
blog.minitab.com great subject matter including the hows whys uses and meanings of control charts, capability measures, hypothesis testing.....many topics
minitab.com a variety of statistical subject matter
As well as in the attachments section (see above at top of this page) of Elsmar Cove, very valuable and practical info there.
To Bev's point above, to provide a useful answer, the particulars of the process in question should be shared or identified....hope this helps - optomist1