Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Participants were randomized to treatment condition. However, no description of random sequence generation was provided.
Allocation concealment (selection bias)	Low risk	“The 358 subjects were measured at the pretest on the variables on interest before random assignment and before receiving the experimental or control intervention. This procedure ensured that neither the investigators nor the subjects would know who was to be assigned to the experimental or control group after the pre‐test”.
Blinding of participants and personnel (performance bias)	High risk	Blinding of participants and personnel was not possible due to the nature of the intervention and study design.
Blinding of outcome assessment (detection bias)	Unclear risk	No description of blinding of outcome assessment was provided.
Incomplete outcome data (attrition bias)	Low risk	“… we concluded that differential attrition was not a significant problem in this study”.
Selective reporting (reporting bias)	Low risk	No evidence of reporting outcome selectively was detected.
Other bias	Low risk	No other potential biases were detected.