Stotts 2006.

Methods	Pilot RCT.
Participants	31 male treatment‐seeking cocaine abusers. USA.
Interventions	Two‐session MI intervention with informative biological EEG/ERP feedback (n=17) or a minimal control condition who had two brief meetings with an experienced research assistant weekly over two weeks (n=14).
Outcomes	Physiological primary: Cocaine‐positive urine screens. Non‐physiological primary: Proportion of self‐reported cocaine use days. Secondary: Readiness to change (URICA). Data not reported.
Notes
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	"randomised".
Allocation concealment (selection bias)	Unclear risk	Insufficient information to permit judgement.
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	"Posttreatment assessment was conducted at 1‐week post‐study by clinic staff blind to study condition."
Incomplete outcome data (attrition bias) All outcomes	Unclear risk	Only subjects with data at both time points were analysed (27/31 = 13% attrition). Reasons for missing data not reported. ITT not performed.
Selective reporting (reporting bias)	Low risk	The published report included all expected outcomes based on the study hypotheses.
Other bias	Low risk	EEG screening to validate self‐report. There were no differences between groups at baseline. No additional sources of bias appear to be present.