{HEAD ~ The Davison Attrition Index}, DI, is determined by {TAIL ~ the following procedure} 
is determined by
{ HEAD ~ The Davison Attrition Index } , DI , is determined by { TAIL ~ the following procedure }
HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH REL REL REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL