prabu

• Oct 25th, 2006

 

Upper tolerance limit (UTL)

kurtz182

 Profile Answers by kurtz182 Questions by kurtz182

• Dec 24th, 2009

 

A) UCL (Upper Control Limit)

Upper and lower control limits indicate the threshold at which the process output is considered statistically 'unlikely' and are drawn typically at 3 'standard errors' from the center line.  If the process is in control, all points will plot within the upper and lower control limits.  Any observations outside these limits, or systematic patterns within, suggest the introduction of a new source of variation known as a special cause.  When special causes arise, they indicate issues that need to be addressed in order to bring the process back under control.