All stages in the collection, validation and production of these statistics are led by professional statisticians working for the contractor and statisticians from the Government Statistical Group.
Mae pob cam wrth gasglu, dilysu a chynhyrchu'r ystadegau hyn yn cael eu harwain gan ystadegwyr proffesiynol sy'n gweithio i'r contractwr ac ystadegwyr o Grŵp Ystadegol y Llywodraeth.