Recital (29)

With the aim of ensuring the highest coverage quality, Member States should use estimation methods to achieve an accurate estimate of the total population at national level. Member States should be able to use estimation methods for more detailed breakdowns, including geographical breakdowns. A substantial lack of knowledge of individual characteristics, such as age and sex, is inherent to some estimation methods, for example when estimating statistics based on data that are not available from administrative or other sources. Where such estimation methods result in an insufficient level of breakdown detail, Member States should be able to use a dedicated adjustment category in order to estimate the population in all relevant data sets. The use of such adjustment categories, indicating unknown data, provides the necessary flexibility for situations where all available data sources have been used and no further detail can be obtained. Where they use a dedicated adjustment category, Member States should explain their methodology and provide reasons for the use of an adjustment category in the relevant quality reports.