Further details of the changes to survey method, sample design, estimation approaches and the effects of applied caps are available in the Great Britain Day Visits background quality report 2021.
Mae rhagor o fanylion am y newidiadau i ddull yr arolwg, dylunio'r sampl,r dulliau amcangyfrif ac effeithiau’r capiau a ddefnyddir ar gael yn Adroddiad Ansawdd Cefndir 2021 GBDVS.