Appendix A. Testing methods
Contract sampling and testing
A judgemental sampling approach was used to select our sample of ten contracts for testing at each health service. Visiting medical officer (VMO) listings for the period ending 30 June 2011 contained on average 50 VMOs per site, therefore we ensured approximately 20 per cent coverage across the VMO population for each hospital.
The judgemental sampling approach was chosen to ensure a representative selection covering a range of variables, including: