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