In this data series a person is defined as being in persistent poverty if he or she is in relative income poverty in at least 3 out of 4 consecutive years.
Yn y gyfres ddata hon diffinnir person fel eu bod mewn tlodi parhaus os yw ef neu hi mewn tlodi incwm cymharol am o leiaf 3 allan o’r 4 blynedd yn olynol.