Barring the 10% persistent absence threshold, the definitions and calculations involved in the collection have not changed, so comparability over time has not been affected.
Nid yw'r diffiniadau a'r cyfrifiadau sy'n gysylltiedig â'r casgliad wedi newid, heblaw am y trothwy 10%, felly nid yw cymaroldeb dros amser wedi cael ei effeithio.