774,750 items of data are available, covering 502,403 participants.
Some values have special meanings defined by Data-Coding 1313
Array indices run from 0 to 14.
- There are 11903 distinct values.
- Mean = 2000-10-18
- 7398 items below graph minimum of 1964-03-31
- 2389 items have value 1904-04-04 (Date in or before calendar year of birth)
This the date at which a participant is first recorded (according to the record sources available to UK Biobank) at the location given in Field 22702
and Field 22704
(or the more precise, but restricted, Field 22701
and Field 22703
Note that, when data is supplied to approved researchers, the array index of dates will not necessarily be in the same order as the dates themselves as UK Biobank does not itself receive location data in chronological order.
Please be aware that there are some inherent inaccuracies in the date of a change of address as it will often correspond to the date the address was changed in the corresponding IT system, rather than the actual address change, due to delays in participants informing UK Biobank or external agencies that they have moved. In addition, we have identified a number of dates that have been incorrectly processed in the construction of data-field 22700 and which are up to 30 months different from the participant's change of address notification. We are working to correct this issue and will update the data-field in due course.
Coding 1313 defines 1 special value:
- 1904-04-04 represents "Date in or before calendar year of birth"