How to conduct stratified randomization in Stata

[Iche Anya]

Good day all. In a three-arm stratified cluster randomized trial, 18 clusters were randomly selected into three strata (6 clusters in each stratum). Please how can the 6 clusters within each stratum be randomized into three groups (one control and two treatment arms) to achieve 2:2:2 allocation?

[Joseph Coveney]

There are a few user-written commands for randomization (ralloc, randomize, ccrand), but you can do stratified random allocation from scratch easily.

[Iche Anya]

Thanks for your response. Please can you help out with both of your suggestions?

[Brad Anderson]

Well you can search for the programs and install. I've used ralloc. It's downloadable from ssc. Haven't used either of the other mentioned programs.

[Iche Anya]

Thanks Brad. Will give it a try.

[Steve Samuels]

help randomly assign

finds other contributed commands at SSC. John Ternovski's stratarand looks like a good one for you. As you are randomizing clusters, start with a dataset of 18 observations, containing just the stratum & cluster variables, then merge the treatment assignments with your full data set.

To do the calculation from scratch, see this UCLA page.

[Iche Anya]

Thanks very much Steve. The link is very helpful.