Why does the number of participants not match between Showcase and the UKB-RAP?

There are two main reasons for a difference in participant counts for a field:

1.     Showcase is regularly augmented with new data.

After being uploaded to Showcase, new data is added into the UKB-RAP by our partners at DNAnexus as a part of a new RAP Data Release Version. This results in a short lag before the UKB-RAP is updated. Researchers are notified once data included in the most recent Showcase Refresh becomes available on the UKB-RAP.

The most recent date when new data was added to Showcases can be found in the past timelines page: https://www.ukbiobank.ac.uk/enable-your-research/about-our-data/past-data-releases.

The dates of the RAP Versions can be found in the DNAnexus documentation Version page: https://dnanexus.gitbook.io/uk-biobank-rap/getting-started/data-release-versions.

Data within a research group's RAP storage reflects the data available within the RAP Data Release Version active at the time the RAP project was dispensed. The dispense date (YYYYMMDD format) is included in the name of the Dataset Record item in the project. 

If the dispense date is earlier than the RAP Version date, then researchers can dispense a new RAP project to receive the new data (See the RAP documentation: https://dnanexus.gitbook.io/uk-biobank-rap/getting-started/creating-a-project). If the dispense date for the project is later than the RAP Version date, the project will include all data available within the UKB RAP for the relevant application tier. You can keep up-to-date with upcoming releases by visiting our Future data release timelines page.

2.    Each UK Biobank participant can withdraw consent to the use of their data at any time.

Since 2006 approximately 1,200 participants have withdrawn. When a participant withdraws, their data is removed from the UKB-RAP. However, the numbers listed on Showcase are only updated when there is a Showcase Refresh. The most recent refresh date can be found on the timelines page. This means that the numbers listed in Data Showcase are likely to be slightly different from the numbers available on the UKB-RAP. 

If neither of these reasons explains the difference, it would be necessary to check that the fields being compared are actually equivalent. Most fields on the UKB-RAP have a link to the equivalent Data Showcase page (This link can be found in the Cohort Browser when adding a column to a cohort). Most fields on the UKB-RAP have the same field number in Data Showcase. If you are still concerned, please contact us with precise details of which field(s) you are looking at.