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According to Article 7(2) of Regulation 2018/1091, modules in 2020 shall be collected only on the main frame. However, where countries collect modules on the frame extension, Eurostat accepts such data in 2020. It's true that not all countries opt for main frame plus frame extension and this might lead to inconsistencies for module specific variables (i.e labour, other gainful activities or manure management) in the comparability between countries in data dissemination. In addition, when a table includes both core variables and module specific variables (i.e labour, other gainful activities or manure management), for the country which collected core on main frame plus frame extension and module only on main frame, the totals of core variables are not computed over the same scope as the totals of the module variables. On the other handTo put it differently, using main frame plus frame extension for core variables and main frame for module specific variables in the same table might lead to biased interpretation. Imagine a user is interested to calculate AWU/UAA, hence the ratio would be wrong as both variables are drawn from two different populations. Alternatively, restricting the data dissemination, -in which core and module variables are used, to only main frame would result in loss of information and comparability over time, but it would increase the comparability across countries in a given year. So there is a clear trade-off. YetYet, to increase the comparability of the data across time, Eurostat decided to disseminate main frame and main frame plus frame extension for specific countries in data publications.
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