In order to ensure the quality, and in particular the comparability, of the data provided by the Member States, and in order for reliable overviews to be drawn up at Union level, the data used should be based on the same concepts, and should refer to the same reference date or period.
Chun cáilíocht na sonraí a chuireann na Ballstáit ar fáil, ó thaobh inchomparáideachta de go háirithe, a áirithiú, agus chun forbhreathnú iontaofa a tharraingt suas ar leibhéal an Aontais, ba cheart na sonraí a úsáidtear a bheith bunaithe ar na coincheapa céanna, agus ba cheart iad a bheith ag tagairt don dáta tagartha céanna nó don tréimhse thagartha chéanna.