RT Journal Article SR Electronic T1 Analysis of longitudinal data: choosing and interpreting regression models JF European Respiratory Journal JO Eur Respir J FD European Respiratory Society SP 325 OP 327 DO 10.1183/09031936.93.06030325 VO 6 IS 3 A1 Ware, JH YR 1993 UL http://erj.ersjournals.com/content/6/3/325.abstract AB