Oakeshott 1994.

Methods	Study design: C‐RCT Unit of allocation: practices Stratification by: number of partners and number of radiographic examinations requested Type of comparison: PEM only vs. nothing group A: control group B: guideline + distribution letter
Participants	Physicians Clinical speciality: general practice/family medicine Level of training: fully trained (e.g., consultant) Setting/country: general practice/UK
Interventions	The PEM studied in this report consisted of the guidelines for examinations of the chest, limbs and joints, and spine taken from the RCR guidelines. The RCR guidelines aimed to encourage more appropriate use of diagnostic radiology and so reduce the use of clinically unhelpful x‐rays. The guidelines were printed verbatim on 2 sides of a sheet of A4 paper, which was then plasticised
Outcomes	3 process outcomes: relevant positive findings at radiology radiological request forms giving physical findings proportion of radiology requests conforming to the guidelines
Notes	‐
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Author could not confirm the method to generate the sequence (P. Oakeshott, personal communication)
Allocation concealment (selection bias)	Low risk	COMMENT: the unit of allocation is by physician and allocation was performed on all units at the start of the study
Baseline characteristics similar (selection bias)	Unclear risk	No report in text or tables of provider characteristics
Baseline outcome measurements similar (selection bias)	Low risk	COMMENT: we judge that no important difference is present across the study groups
Incomplete outcome data (attrition bias) All outcomes	Unclear risk	No information was provided
Blinding of outcome assessment (detection bias) All outcomes	Low risk	Quote, pg. 197: "conformity was assessed by P 0 and J W who were unaware which practices had been sent the guidelines"
Contamination protection (contamination bias)	Low risk	Quote, pg. 197: "practices were stratified by number of partners and number of radiographic examinations requested, and randomized into two groups"
Selective reporting (reporting bias)	Low risk	All relevant outcomes in the methods section were reported in the results section
Other bias	Low risk	There was no evidence of other risks of bias