The computer implemented method 1 further comprising determining {HEAD ~ said improved index performance indicator} by using {TAIL ~ a query box} 
The computer implemented method 1 further comprising determining { HEAD ~ said improved index performance indicator } by using { TAIL ~ a query box }
OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL