Copeland 2001.

Methods	RCT.
Participants	229 Australian cannabis users.
Interventions	1. 6‐session CBT (including elements of MI) (n= 78) 2. 1‐session CBT (including elements of MI) (n= 82) 3. delayed treatment control group (n= 69).
Outcomes	Physiological primary: None. Non‐physiological primary: Daily amount of cannabis use in last month, cannabis dependence, proportion of cannabis related problems. Secondary: None.
Notes
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	"...randomised to one of three conditions".
Allocation concealment (selection bias)	Unclear risk	Insufficient information to permit judgment.
Blinding (performance bias and detection bias) Patients and providers	Unclear risk	No blinding but the outcome measurements are not likely to be influenced by lack of blinding due to validation with physiological measurement.
Blinding (performance bias and detection bias) Assessors	Low risk	"...follow‐up was conducted by an independent researcher "blind" to the subject's treatment allocation."
Incomplete outcome data (attrition bias) All outcomes	High risk	26% attrition at a median of 237 days follow‐up (individual follow‐up durations, range: 102‐553 days). Drop out was balanced across groups. No reasons for drop‐out were stated. "Analyses were conducted on an intention‐to‐treat basis." A best‐case scenario was reported.
Selective reporting (reporting bias)	Low risk	The published report included all expected outcomes based on the study purposes.
Other bias	High risk	17% had sought assistance to moderate their use in the time between their participation in this study and follow‐up. They used urinalysis of cannabinoid levels as a validation of self‐reported cannabis use. Differences between groups at baseline were not reported.