[Ly Tran]

Thanks for your reply, Rich. Frequency matching means that the frequency of matching variables are equal between 2 groups. Ex: if 10% of group A is female, we want that group B has 10% female too (frequency matched on sex). Do you know what commands can help?

[Hao Duong]

I try the syntax instructed by Clyde Schechter (note 3 in #4) but it does not work, did I miss anything?
Thank you!
Hao

. contract age_enrol_cat sex, freq(2*desired)
2 invalid name
r(198);