The NDC is an annual pupil level collection of statutory baseline and end of key stage (Foundation Phase, Key Stage 2 and Key Stage 3) teacher assessment data.
Casgliad blynyddol ar lefel disgyblion o ddata asesu athrawon llinell sylfaen statudol a diwedd cyfnod allweddol (Cyfnod Sylfaen, Cyfnod Allweddol 2 a Chyfnod Allweddol 3) yw'r CDC.