New questions are developed by survey experts and many have been subject to external peer review, with a subset also being cognitively tested with members of the public.
Caiff cwestiynau newydd eu datblygu gan arbenigwyr arolygon ac mae llawer wedi’u hadolygu gan gymheiriaid allanol, gydag is-set hefyd wedi bod drwy brawf gwybyddol gydag aelodau o’r cyhoedd.