Selection bias decisions for trials that reported unadjusted analyses: comparison of results obtained using method details alone versus results obtained using method details and trial baseline informationa
	Reported randomisation and allocation concealment methods	Risk of bias judgement using methods reporting	Information gained from study characteristics data	Risk of bias using baseline information and methods reporting
	Methods are unclear	Unclear risk	Baseline imbalances present for important prognostic variable(s)	High risk
			Groups appear similar at baseline for all important prognostic variables	Low risk
			Limited or no baseline details	Unclear risk
	Would generate a truly random sample, with robust allocation concealment	Low risk	Baseline imbalances present for important prognostic variable(s)	Unclear riskb
			Groups appear similar at baseline for all important prognostic variables	Low risk
			Limited baseline details, showing balance in some important prognostic variablesc	Low risk
			No baseline details	Unclear risk
	Sequence is not truly randomised or allocation concealment is inadequate	High risk	Baseline imbalances present for important prognostic variable(s)	High risk
			Groups appear similar at baseline for all important prognostic variables	Low risk
			Limited baseline details, showing balance in some important prognostic variablesc	Unclear risk
			No baseline details	High risk
	aTaken from Corbett 2014; judgements highlighted in bold indicate situations in which the addition of baseline assessments would change the judgement about risk of selection bias compared with using methods reporting alone. bImbalance was identified that appears likely to be due to chance. cDetails for the remaining important prognostic variables are not reported.