Stotts 2001.

Methods	RCT.
Participants	105 US cocaine‐dependent men and women aged 18‐50 years admitted to a university medical centre.
Interventions	MI vs detox‐only. The group sizes were not reported. The detox only conditions was "...a multi component intervention consisting of daily visits, interaction with research assistants, education, and graphing and feedback of daily urine results, as well as bonus money and further treatment contingent on successful completion of the program."
Outcomes	Physiological primary: Cocaine‐positive urine samples. Non‐physiological primary: Cocaine use. Secondary: Treatment retention (completion of detox program). Readiness to change (Processes of Change Scale).
Notes	We sent an email on April 29th 2010 requesting the group sizes. On June 4th we contacted Brad Lundahl, author of a systematic review for effect size information. He gave us effect size data.
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	"...randomly assigned..."
Allocation concealment (selection bias)	Unclear risk	"...randomly assigned..."
Blinding (performance bias and detection bias) Patients and providers	Low risk	No blinding, but most outcomes were physiological and also used to validate self‐reports, and not likely to be influenced by lack of blinding.
Blinding (performance bias and detection bias) Assessors	Low risk	Insufficient information to know whether assessors were blinded. But most outcomes were physiological and also used to validate self‐reports, and not likely to be influenced by lack of blinding.
Incomplete outcome data (attrition bias) All outcomes	High risk	Intention to treat of the full sample (N =105) were conducted on completion of the DP. The number of participants randomised to each condition is not reported. Analysis of urine samples were conducted on 51 completers.
Selective reporting (reporting bias)	Low risk	The published report included all expected outcomes based on the study hypotheses.
Other bias	Low risk	Urineanalysis to validate self‐report. There were no differences between groups at baseline. No additional sources of bias appear to be present.