Clinical trial - stratified randomization

Hi all,
There is something very basic I don't get about stratified randomization and I was hoping you might be willing to help me with.
Say I have a clinical trial for which I would like to recruit 90 patients.
I have two alternative treatments I want to test.
I also have 2 baseline measures by which I would like to stratify my subjects (to simplify assume these are age and sex).
So my subjects should be stratified into 4 groups and randomized into two treatments.
From what I gather (must admit - I'm not a statistician), I basically need to create 4 different randomization lists. I also understand these can be created with additional blocks.
However - How long should these lists be? I do not know in advance how many subjects I will have in each group. Do I basically make 4 lists of 90?
Is there a specific (free) software or web app that is recommended to do this?
Many thanks!!


New Member
Clinical trial stratified randomization

Anyone have any idea how this trial went.It ended in January but I cant find anything about it.


Less is more. Stay pure. Stay poor.
Yes, you would make four pools to select from. The number people in each pool should be all that fit the group, if not you need a reason and method for the selection of pool applicants. The number of people you select from each pool depends also on your research agenda. If you want even weights, you would just select 24 from each group and randomize treatment to each pool selections independently. Though you would end-up with 98 subjects.