This will be a basis for analysing the differences between other sources, such as the Pupil Level Annual School Census and the National Survey for Wales.
Bydd hyn yn sail i ddadansoddi’r gwahaniaethau rhwng ffynonellau eraill, megis y Cyfrifiad Ysgol Blynyddol ar Lefel Disgyblion ac Arolwg Cenedlaethol Cymru.