The included surveys were from Australia, Canada, New Zealand, multiple surveys and question sets from the UK, and 5 question sets from the Washington Group on Disability Statistics.
Roedd yr arolygon a gynhwyswyd yn dod o Awstralia, Canada, Seland Newydd, arolygon a chyfresi cwestiynau niferus o’r DU, a 5 cyfres o gwestiynau am Ystadegau Anabledd gan The Washington Group.