The Stability of an item describes how 'fixed' the values are. There are four categories:
- Complete - all data has been collected and will never change, an example would be the date at which a participant joined UK Biobank;
- Updateable - all data has been collected, but the values may change over time, an example would be the volume of the initial blood samples collected by UKB which will decrease as new analyses are performed using them;
- Accruing - data is still being gathered;
- Ongoing - data is still being gathered and the values already held may change over time;
- Obsolete - data which has been superceded by other fields and is not recommended for use.