Chan 2003.

Methods
Participants
Interventions
Outcomes
Notes	See Table 8
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	"The subjects were randomly assigned to either a music or no‐music group by the research nurse using a computer‐generated random number series [...]"
Allocation concealment (selection bias)	Low risk	"computer‐generated random number series contained within closed opaque envelopes."
Blinding (performance bias and detection bias) Subjective outcomes	High risk	Patients aware of group allocation.
Blinding (performance bias and detection bias) Objective outcomes	Unclear risk	Objective outcomes not addressed by this study.
Incomplete outcome data (attrition bias) All outcomes	Low risk	"all subjects completed the STAI form again and assessed their degree of pain" "220 women were entered into the trial and all of them completed the study"
Selective reporting (reporting bias)	Unclear risk	Unknown if selective outcome reporting.
Protection from contamination?	Low risk	Interventions administered on an individual basis.