associating a cause of said variation based upon {TAIL ~ a comparison} of said one of said measured characteristics to measured characteristics associated with the remaining processing regions of {HEAD ~ said subset} 
associating a cause of said variation based upon { TAIL ~ a comparison } of said one of said measured characteristics to measured characteristics associated with the remaining processing regions of { HEAD ~ said subset }
OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD