Randomization using RALLOC with stratification

[May Blake]

Hi,

I am trying to generate a random sequence with 4 treatment groups into 2 strata and using either block sizes of 4 or 8. I set my observations at 400 to get 100 in each treatment group. I use the following code below. I am having a problem afterwards where the strata option is not being randomized. it shows all 1s then all 2s below. How do I get both the treatment groups and the gender randomized within the block sizes? Thank you.


ralloc blknum blzsize treat, nsubj(400) osize(2) equal ntreat(4) saving(mytrial) shape(long) seed(date) trtlab(0 1 2 3) strata(2) multif

set seed 314159
gen random = uniform()

sort blknum StratID random

[Tiago Pereira]

I did not understand your question. It seems you want participants to be randomized by sex.

Your code is generating a random sequence for a trial with 800+ participants:

List1: Male: 100+ participants per treatment group (100,100,100,100)
List 2: Female: 100+ participants per treatment group (100, 100,100,100)

I have put a plus sign because the total number of participants should be slightly larger than 800, since the number of blocks is random, and block sizes should always be 4 or 8.

So, essentially, you have two lists. If the participant is male, he will be randomized according to list 1 (StratID==1). Otherwise, she will be randomized according to list 2 (StratID==2).
Do not change the order of the randomization list.

[May Blake]

Tiago, Thank you. this was very helpful!