In their Income Dynamics report they define a person to be in persistent poverty if he or she is in relative income poverty in at least 3 out of 4 consecutive years.
Yn eu hadroddiad Dynameg Incwm maent yn diffinio person i fod mewn tlodi parhaus os yw ef neu hi mewn tlodi incwm cymharol am o leiaf 3 allan o 4 blynedd yn olynol.