evaluating {TAIL ~ a difference} between the forecasted device performance characteristic and {HEAD ~ a target device performance characteristic}; and 
evaluating { TAIL ~ a difference } between the forecasted device performance characteristic and { HEAD ~ a target device performance characteristic } ; and
OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH