dummy randomization with ongoing patients

[noda6003]

Hi,

I want to create a dummy randomisation list to randomly assign 2 treatments for pat id's. i found many examples but if i get a new pat id then the program should randomly assign one treatment and not change the existing treatment groups. is there any existing program which does or an example would be appreciated. assigning trt A and trt B like below

pat_id       trt

101           trt A

102          trt B

103          trt B

104          trt A

[Kurt_Bremser]

Keep a dataset with the existing values, and randomize only the new ones:

data have;
infile cards dlm=',';
input pat_id $ trt $;
cards;
101,trt A
102,trt B
103,trt B
104,trt A
;
run;

data add;
input pat_id $;
cards;
105
;
run;

data want;
set
  have
  add
;
if trt = '' then trt = ifc(rand('normal',1) > .5,'trt A','trt B');
run;

[FreelanceReinh]

@Kurt_Bremser: I think you mean the 'uniform' distribution, not the 'normal' distribution (for an allocation ratio of 1:1).

[andreas_lds]

How do you get a new patient?

Without knowing the program you use for the initial assignment of treatments, it is hardly possible to suggest something useful, except for the most obvious: exclude the observations with non-missing trt variable when assigning trt.