Grant 2011.

Methods	Design: pair‐matched cluster‐randomised trial Study period: Dates not stated Pre‐test: hand hygiene observations over a 2‐week period with no sign Post‐test: hand hygiene observations over a two 2‐week period with 1 of 2 signs displayed 4 matched pairs of units in one hospital in the USA
Participants	3 categories of healthcare workers: MDs, nurses, and ancillary workers
Interventions	1 of 2 signs displayed. Signs had message related to personal consequences or to patient consequences
Outcomes	Hand hygiene compliance
Notes	Incorrect analysis: analysed by units rather than matched analysis Covert observation so observer effect unlikely to be a threat Funding source: None Declaration of interest: None
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Not specified how random allocation was done
Allocation concealment (selection bias)	Low risk	Unit of allocation was the ward and was done at the start of the study
Blinding of participants and personnel (performance bias) All outcomes	Low risk	Participants were aware of the signs but were not informed of the research underway
Blinding of outcome assessment (detection bias) All outcomes	Low risk	Observers were blinded
Incomplete outcome data (attrition bias) All outcomes	Low risk	Missing data (missed opportunities) unlikely to be different in each arm. All units remained in study
Selective reporting (reporting bias)	Low risk	No evidence of selective reporting
Other bias	Low risk	No evidence
Baseline outcomes	Low risk	Similar baseline hand hygiene rates for all 3 types of healthcare workers
Baseline characteristics	High risk	No baseline characteristics presented
Protection from contamination	Low risk	Participants were aware of the signs but were not informed of the research underway