Hello, I would like to identify the first occurrence of an intervention for 4 different interventions. In other words, of the 4 interventions which one occurred first. I have included sample variables and code. thanks!   sample data set: patient1   intervention1  int1_date  intervention2  int2_date  intervention3  int3_date  intervention4  int4_date patient2  ............   data test2; set test; by ID; if (int1_date < int2_date and int1_date < int3_date and int1_date < int4_date) then int =1; if (int2_date < int1_date and int2_date < int3_date and int2_date < int4_date) then int =2; if (int3_date < int1_date and int3_date <int2_date and int3_date < int4_date) then int =3; if (int4_date< int1_date and int4_date <int2_date and int4_date < int3_date) then int =5; else int = 5; run; ... View more