Randomization and Masking
Consenting GPs were randomized to receive either enhanced training as described in the next section (intervention group) or a refresher in identification and referral alone (control group). Intervention GPs were encouraged to treat nonacute child mental health problems if parents and patients were willing; control GPs were instructed to continue referring to a CMHC. All GPs received support from the program as before.Randomization used the Stata routine ralloc to create a nonfactorial balanced list of allocations in which GPs were assigned in blocks of 2 or 4 to the intervention or control group, such that 2 GP characteristics (practice size [small: <20 patients of all ages/d; large: ≥20 patients of all ages/d] and ownership [private vs public]) were balanced in the intervention and control groups. Practice ownership was hypothesized as important for balancing because privately insured patients might have more access to mental health services outside the collaborative care network,Research assistants assessed outcomes by telephone. Assistants knew which GP the child had seen but were blinded to training assignments. GPs were not given SDQ scorings but knew that it had been administered.