Variations in {HEAD ~ differences} between target web site data values and corresponding average and bounding web site data values over {TAIL ~ time} determines improvement and success of the target web site 
over
Variations in { HEAD ~ differences } between target web site data values and corresponding average and bounding web site data values over { TAIL ~ time } determines improvement and success of the target web site
OTH OTH HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH REL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH