To maximise the data that could be analysed from the survey, imputation was carried out to model missing values within responses, based on other values (responses) provided within the survey.
Er mwyn manteisio i’r eithaf ar y data y gellid ei ddadansoddi o’r arolwg, priodolwyd i fodelu gwerthoedd coll mewn ymatebion, ar sail gwerthoedd eraill (ymatebion) a ddarparwyd yn yr arolwg.