The Office for National Statistics (ONS) has recalibrated the weights of Annual Population Survey datasets for periods covering the year ending 2020 quarter 1 to the year ending 2021 quarter 4.
Mae'r Swyddfa Ystadegau Gwladol wedi oedi cyn diweddaru'r gyfres amser rhwng Chwarter 1 2012 a Chwarter 4 2019 i ganolbwyntio ar ddatblygu dulliau o wella ansawdd data a lleihau amlder y diwygiadau.