The National Centre for Social Research (NatCen) were therefore commissioned to develop and test a set of demographic survey questions, response options, and guidance.
Cafodd y Ganolfan Genedlaethol Ymchwil Gymdeithasol (NatCen) ei chomisiynu felly i ddatblygu a phrofi cyfres o gwestiynau arolwg demograffig, opsiynau ymateb, ac arweiniad.