As regards the basis on which the data is collected, Member States shall take any measures they deem appropriate to maintain the quality of the results. Member States may produce the necessary statistical data by using a combination of the following different sources:
((a))
surveys, where reporting units are asked to give timely, accurate and complete data;
((b))
other appropriate sources, including administrative data, if these are appropriate in terms of timeliness and relevance;
((c))
appropriate statistical estimation procedures.