METHODS	Newly enrolled Medicare beneficiaries in Hawaii from 25 September 1995 through 31 August 1996 were randomly assigned to one of three groups : Group 1 , no letter ( n = 2144 ) ; Group 2 , influenza immunization reminder letter only ( n = 2213 ) ; or Group 3 , pneumococcal and influenza immunization reminder letter ( n = 2171 ) .\