The Array property of a Data-Field describes whether there are multiple data items for a given participant instance. There are two categories:
- Single - only one data item is present for each participant, for instance the answer to "What is your favourite colour of the rainbow?"
- Multiple - more than one data item may be present for each participant, for instance the answer to "Which colours of the rainbow do you like?"
Where tests were performed multiple times during the same examination/visit (e.g. repeated blood pressure readings at the UK Biobank Assessment Centres) then the results for each 'round' of measurement are presented as an array.