Hiscock 2008.

Methods	Design: Parallel, cluster‐randomised controlled trial Unit of randomisation: Mother and child heath centre Follow‐up: 21 months Study dates: 2004 to 2006
Participants	Participants: 733 mothers Mean age of parents: Intervention 33.0 (SD 4.8; range: NR) years; control 33.3 (SD 4.7; range: NR) years; mean, SD, range for entire sample: NR Age of child: 8 months (mean, SD, range: NR); number of boys and girls: NR Ethnicity: Not reported Number randomised: 733 (intervention 329; control 404) Country & setting: Australia; multi‐site; recruited from community settings; intervention delivered in the community Eligibility criteria: Parents of children aged 6 months attending community well‐child clinics
Interventions	Two conditions: Group‐based parent training (Toddlers Without Tears); usual primary care Duration of intervention: 7 months Therapist training: Nurses trained by a paediatrician and child psychologist
Outcomes	Externalising problems: Child Behaviour Checklist 1.5 to 5 years ‐ externalising, mother‐reported Internalising problems: Child Behaviour Checklist 1.5 to 5 years ‐ internalising, mother‐reported Timing of outcomes: Outcomes reported for 3 years follow‐up (12 and 18 months data also reported in the study but not entered in the review) Secondary outcomes/adverse events: No other outcomes relevant to this review specified
Notes	Level of prevention: Primary Funding: Philanthropic Organisation, William Buckland Foundation, Telstra Community Development Fund
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Maternal and child health centres were cluster‐randomised using a computer‐generated allocation sequence
Allocation concealment (selection bias)	Low risk	Study investigators reported that "an independent statistician randomly allocated maternal and child health centres"
Blinding of participants and personnel (performance bias) All outcomes	High risk	Participants: Study investigators reported "masking occurred at randomisation, with group allocation concealed from researchers and participants until allocation was complete", however, no specific additional measures taken to reduce the risk of bias that might result from differential behaviours by participants were found after allocation was complete Personnel: The design of the study means personnel delivering the intervention would be aware which groups had been assigned to the different study conditions
Blinding of outcome assessment (detection bias) Independent observer reported outcomes	Low risk	There were no independent observer‐rated outcomes
Blinding of outcome assessment (detection bias) Parent reported outcomes	High risk	Outcomes were mother‐reported, study investigators reported "masking occurred at randomisation, with group allocation concealed from researchers and participants until allocation was complete", however, no specific additional measures were reported after allocation was complete
Incomplete outcome data (attrition bias) All outcomes	Low risk	37 out of 329 families in the intervention group and 40 out of 404 families in the control group left the study early. Reasons for leaving early were not reported. Intention‐to‐treat analysis was done
Selective reporting (reporting bias)	Low risk	The published report includes all expected outcomes, including those that were prespecified
Other bias	Low risk	The study appears to be free of other sources of bias. This was a cluster‐randomised trial, the study authors reported ICC and accounted for clustering in their analysis by using multilevel models