Walters 2000.

Methods	Design: RCT Follow‐up: 6 weeks Attrition: 14%
Participants	Mean age (years): 19.7 Sex: 40% female N participants: 37 Allocation: not reported Setting: psychology department mass testing session; higher risk students Country: USA
Interventions	Programme type: motivational interviewing Set‐up: group single session Key components: values clarification; suggestions to promote responsible drinking; information about campus resources Duration: 2 h Control: assessment only
Outcomes	Outcomes: consumption; weekly and peak blood alcohol concentration Measures: Short Index of Problems; Alcohol Use Disorders Identification Test; Check Up to Go (CHUG; Q/F index)
Funding and Declared Conflicts of Interest	No information
Notes	AUDIT outcomes not reported; final group numbers not reported
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Insufficient information to permit judgement
Allocation concealment (selection bias)	Unclear risk	Insufficient information to permit judgement
Incomplete outcome data (attrition bias) All outcomes	Low risk	Low attrition (14%)
Selective reporting (reporting bias)	High risk	Not all outcomes were reported (e.g. AUDIT results)
Blinding of participants and personnel (performance bias) All outcomes	High risk	Not possible to blind participants to intervention. Insufficient information to make a judgement about blinding of therapists
Blinding of outcome assessment (detection bias) All outcomes	Low risk	"In order to increase valid responding, all responses were anonymous and participants were identified only by numbers. All measures were scored by trained raters who were unaware of treatment condition"
Unit of Analysis issues	Low risk	Not applicable