The main source of data used is the Wales National Workforce Reporting System (WNWRS) which has been supplied and validated by NHS Wales Shared Services Partnership.
Prif ffynhonnell y data a ddefnyddir yw’r System Adrodd Genedlaethol y Gweithlu Cymru (WNWRS) sydd wedi'i gyflenwi a'i ddilysu gan Bartneriaeth Cydwasanaethau'r GIG.