Use a study ID consisting of 3 components in the format XXXXXX.XXXX:
Study IDs are stored as character values to ensure that zero place holders are not dropped. The randomisation number is assigned sequentially at each site after randomisation. A decimal point is placed between the site code and randomisation number. This allows sites to monitor their recruitment and ensures the ID can be easily converted to a numerical value if manipulations are required. The study number ensures that samples can be identified across studies.
The following site codes have been used in previous Australasian multicentre trials and have been retained for continuity:
Auckland City Hospital
Hawke’s Bay Hospital
North Shore Hospital
Tauranga Hospital (Bay of Plenty)
To deal with unit of analysis issues, there are two common solutions: