| ID | var1 | var2 |
| 01 | Y | Cancer |
| 01 | Y | Death |
| 01 | Y | Prolongs Hospitalization |
| 01 | Y | Life Threatening |
| 02 | N | Overdose |
| 02 | N | Death |
| 02 | N | Disability |
| 02 | N | Cancer |
| 02 | N | Other |
| ID | ID1 | var1 | var2 |
| 01 | 1 | Y | Cancer |
| 01 | 2 | Y | Death |
| 01 | 3 | Y | Prolongs Hospitalization |
| 01 | 4 | Y | Life Threatening |
| 02 | 1 | N | Overdose |
| 02 | 2 | N | Death |
| 02 | 3 | N | Disability |
| 02 | 4 | N | Cancer |
| 02 | 5 | N | Other |
数据管理：插入新变量ID1：按ID分组，每组用ID1顺序编号（如表2）；table1数据集命名为ae，table1数据集命名为ae1。
sample sas code：
proc sort data=ae out=ae0;
by id;
run;
data ae1;
set ae0;
by id;
if first.id then id1=1;
else id1+1;
run;