Monitoring the same set of products at regular intervals in the same shops will not give an accurate image of the general situation (as observed in Cyprus this year)[6] because the behaviour of the shops concerned will presumably be distorted by the very existence of the monitoring.
Als periodiek dezelfde producten in dezelfde winkels worden gecontroleerd, ontstaat geen juist beeld van de algemene situatie (dit is gebleken op Cyprus dit jaar[6]).