A randomized (control trial) may involve some cohorts of parents.
Randomized trials can be constituted-of-or-filled-with curriculas.
A randomized trial can be constituted-of-or-filled-with glucosamine.
A randomized (control trial) may pertain-to a primary treatment.
Researcher may do a randomized (control trial) of a primary treatment.
Surveys of randomized trials may find that something-is-the-case.