Among the employed are included all persons aged 15 and more who during the reference week: 1) performed for at least one hour any work generating pay or income, i.e. were employed as a paid employees, worked on their own (or leased) agricultural farm, or conducted their own economic activity outside agriculture, assisted (without pay) in work on family agricultural farm or in conducting family economic activity outside agriculture, 2) had work but did not perform it: a) due to sickness, maternity leave or vacation, b) due to other reasons, but the break in employment: - did not exceed 3 months, - exceeded 3 months, but these persons were paid employees and during that period received at least 50% of the hitherto remuneration (since the 1st quarter of 2006). In accordance with the international standards, among the employed were also included apprentices who entered into occupational training or occupational preparation contract with a private or public employer, if they received remuneration. Due to the methodological assumptions the number of the employed obtained from the LFS does not comprise some categories of persons, who are considered as employed in the establishment survey, e.g.: a) employees living in lodging houses for workers, b) employees working abroad for their Polish employers. In the category of the employed, a distinction was made between full-time workers and part-time workers. This category is calculated on the basis of respondent's declaration related to the main job. The presented data concerning the kind of activity of the main job (economic sections) have been compiled on the basis of the Polish Classification of Activities (PKD), obligatory since the 1st quarter of 2000 (often modified), more significant modifications: - PKD 2004 (obligatory since the 1st quarter of 2005) - PKD 2007 (obligatory since the 1st quarter of 2008).