I'w dynodi'n Ystadegau Gwladol, rhaid i'r Swyddfa Rheoleiddio Ystadegau asesu a barnu bod yr ystadegau swyddogol yn cydymffurfio â'rCod Ymarfer ar gyfer Ystadegau. Mae hynny'n golygu bod yr ystadegau'n cwrdd â’r safonau uchaf o ran ymddiriedaeth, ansawdd a gwerth.
To be designated as National Statistics, the OSR must assess and judge that the official statistics comply with theCode of Practice for Statistics. That means the statistics meet the highest standards of trustworthiness, quality and value.