Patterson 2002.

Methods	Parallel randomised controlled trial.
Participants	Participants: parents of children aged 2‐8 years registered at three GP practices in Oxford. Sex: both mothers or fathers (no further information). Age of parents: not stated. Unit of allocation: individual participant. Number randomised: 116 (60 intervention; 56 control). Number used in analysis: 95‐96 (45‐46 intervention; 50 control). Country & setting: UK; multi‐site (number not stated); recruited from primary care settings; intervention delivered in primary care. Inclusion criteria: scoring above 100 on the Eyberg Child Behaviour Inventory (ECBI). Exclusion criteria: not stated. Ethnicity: 91.4% white, 4.8% Asian, 2.9% mixed race, 1% Black. Baseline characteristics: 14.7% single parents. 13.3% social class I, 39.0% social class II, 22.9% social class III N, 13.3% social class III M, 5.7% social class IV, 5.7% social class V.
Interventions	Two conditions:  Webster‐Stratton parenting program; no‐treatment control. Duration of Intervention: 10 weeks. Length of follow‐up: 3 months; 6 months.
Outcomes	Depressive symptoms (General Health Questionnaire). Anxiety symptoms (General Health Questionnaire). Stress (Parenting Stress Index‐total). Self‐esteem (Rosenberg Self‐Esteem Scale).
Notes	Includes follow up data from Stewart‐Brown 2004.
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Trial investigators report that randomisation was "by tossing a coin in the presence of an independent witness, to treatment or control" (page 473). Review authors judge that the allocation sequence was adequately generated.
Allocation concealment (selection bias)	Low risk	Information reported insufficient for a judgement to be made, but information from trial investigator (email from J Patterson to NH on 23 Oct 2010) indicates that central allocation was used involving a third party not otherwise involved in the trial.
Blinding (performance bias and detection bias) Participants	High risk	Review authors judge that it would not be possible to fully blind participants in this type of study, and found no indication of any specific additional measures taken to reduce the risk of bias that might result from differential behaviours by participants.
Blinding (performance bias and detection bias) Personnel	Low risk	Information reported insufficient for a judgement to be made, but information from trial investigator (email from J Patterson to NH on 23 Oct 2010) indicates that personnel involved in data handling were blind to allocation until after all quantitative data had been collected.
Blinding (performance bias and detection bias) Outcome assessors	Low risk	Information reported insufficient for a judgement to be made, but information from trial investigator (email from J Patterson to NH on 23 Oct 2010) indicates that outcome assessors were blinded during collection and analysis of quantitative data.
Incomplete outcome data (attrition bias) All outcomes	Low risk	At 6 months follow up, 4/60 (7%) were missing from intervention group and 4/56 (7%) were missing from the control group. At 12 months follow up, 16/60 (27%) were missing from intervention group and 13/56 (23%) were missing from the control group. Reasons for missing data not broken down by condition but included increased work commitment, moving away from the area, depression, other life stress, and holiday falling at start of group sessions. Trial investigators report no difference in the proportion of attenders or non‐attenders returning questionnaires at follow up. Review authors judge the numbers of missing data were balanced between conditions.
Selective reporting (reporting bias)	Low risk	Review authors judge that the published report includes all expected outcomes, including those that were pre‐specified.
Other bias	Low risk	The study appears to be free of other sources of bias.