实现观测滞后的方法

此处以ADAE数据集作为示例:

方法一:lag

data adae1; set adam.adae; keep usubjid subjid aedecod aestdtc aeendtc aetoxgrn; proc sort; by usubjid aedecod aestdtc aeendtc aetoxgrn;run;data adae2; set adae1; by usubjid aedecod aestdtc aeendtc aetoxgrn; aeendtc_lst = lag (aeendtc)； if first.aedecod then aeendtc_lst =''; proc sort; by usubjid aedecod descending aestdtc descending aeendtc;run;data adae3； set adae2； by usubjid aedecod descending aestdtc descending aeendtc; aestdtc_nxt = lag(aestdtc)； if first.aedecod then aestdtc_nxt =''; proc sort; by usubjid aedecod aestdtc aeendtc aetoxgrn aeendtc_lst aestdtc_nxt;run;

方法二：retain

data adae1; set adam.adae; keep usubjid subjid aedecod aestdtc aeendtc aetoxgrn; proc sort; by usubjid aedecod aestdtc aeendtc aetoxgrn;run;data adae2; set adae1; by usubjid aedecod aestdtc aeendtc aetoxgrn; length aeendtc1 $20； retain aeendtc1； if first.aedecod then aeendtc1=''； if not first.aedecod then aeendtc_lst = aeendtc1; aeendtc1 = aeendtc; proc sort; by usubjid aedecod descending aestdtc descending aeendtc;run;data adae3； set adae2; by usubjid aedecod descending aestdtc descending aeendtc; length aestdtc1 $ 20； retain aestdtc1； if first.aedecod then aestdtc1 =''； if not first.aedecod then aestdtc_nxt = aestdtc1； aestdtc1 = aestdtc; drop aestdtc1 aeendtc1； proc sort; by usubjid aedecod aestdtc aeendtc aetoxgrn aeendtc_lst aestdtc_nxt;run;

方法三：双set

data adae1; set adam.adae; keep usubjid subjid aedecod aestdtc aeendtc aetoxgrn; proc sort; by usubjid aedecod aestdtc aeendtc aetoxgrn;run;data adae2; set adae1； by usubjid aedecod aestdtc aeendtc aetoxgrn; aeendtc_lst = lag (aeendtc)； if first.aedecod then aeendtc_Ist =''；if not last.aedecod then do i = _n_+ 1; set adae1(keep = aestdtc rename = (aestdtc = aestdtc_nxt)) point = i; end; if last.aedecod then aestdtc_nxt = ''; proc sort; by usubjid aedecod aestdtc aeendtc;run;