Table 1.

Sample eligibility and recruitment

Professional group	Eligibility criteria	Total population meeting criteria	Available number in population following initial exclusions*	Number randomly selected (% of total population)
Chiropractors	Registered with the General Chiropractic Council and the British Chiropractic Association	1071 (100%)	611	611 (57.0%)
Osteopaths	Registered with the General Osteopathic Council	2718 (100%)	1868	1368 (50.3%)
Physiotherapists	Registered with the Chartered Society of Physiotherapy and self-selected as 'musculoskeletal' by speciality	3586** (100%)	3230	1625 (45.3%)
Total =		7375 (100%)	5709	3604 (48.9%)

* Practitioners with addresses outside of the UK and in Scotland were excluded prior to posting invitations, and only one practitioner from each practice was eligible, being randomly selected from each address to avoid contamination (chiropractors and osteopaths only).

** At the time of sampling, there were approximately 30,000 physiotherapists in the UK, of which only 3587 were listed by the Chartered Society of Physiotherapy as 'musculoskeletal' by speciality.