This manual details the procedure for the Symbol digit substitution test. This was administered as web-based questionnaires and participants were invited to complete it remotely.

This resource can be downloaded or viewed using the link: symdigsub_doc.pdf

If you have wget available (typically on linux systems), then you can also obtain a copy using the command

 wget  -nd  biobank.ctsu.ox.ac.uk/ukb/ukb/docs/symdigsub_doc.pdf