The aim of DACSEIS is to advance the provision of reliable information on data quality to accompany statistics databases. Best practice recommendations are prepared for users as well as a discussion of the possibilities for harmonising sampling methods. A main target of DACSEIS is the standardisation and harmonisation of variance estimation methods used to calculate sampling errors, with special emphasis on different national surveys within the European statistical system and their international comparison.A catalogue of applicable instructions and criteria is to be prepared allowing the user to choose among effective procedures of variance estimation for complex sample designs. Results as well as estimation methods are put at the disposal of official, non-official, and other interested users with respect to high quality standards in statistics. This includes the delivery of a best practice manual as well as the source and pseudo codes of all relevant estimation procedures.