Data on economic activity of population aged 15 years and more were prepared on the basis of the sample Labour Force Survey (LFS) carried out quarterly since May 1992 and improved in accordance with the Eurostat recommendations. The survey covers persons who are members of the household selected to the survey. The survey subject is the situation concerning economic activity of the population, i.e. the fact of performing work, being unemployed or economically inactive during the reference week. From the 1st quarter of 2003 to the 2nd quarter of 2012, the data on the Polish population (population aged 15 years and more) coming from the balances prepared on the basis of the National Census of Population and Housing 2002 were used for generalization of the results, that is why the LFS data are not completely comparable to the data for the previous years. Since the 3rd quarter of 2012, the generalization of the survey results onto the overall population has been done with the use of data coming from the balances compiled on the basis of the National Census of Population and Housing 2011. Moreover, there were introduced methodological changes: since the 3rd quarter of 2012, from the survey range have been excluded persons staying outside the household for 12 months or longer; until the 2nd quarter of 2012 - longer than 3 months. Thus, the LFS data since the 3rd quarter of 2012 onwards are not fully comparable with the results from the previous periods. The survey data for the period: between the 1st quarter of 2010 and the 2nd quarter of 2012 were recalculated according to the new methodology and the new basis of the results generalization. Data presented by age groups have been calculated on the basis of the exact date of birth, until the first quarter of 2006 - excluding persons aged 15 years - they were presented according to the year of birth. In some tables, particular components do not sum up to the figures given in the "Total" items due to the computer rounding up. Until 2019, figures below 5 thousand are not presented because of high random error of sample, since the first quarter of 2020 this are figures below 10 thousand. Quarterly data - concern population aged 15 years and more according to the actual place of residence. Since the first quarter of 2016, the previously used calibration of weights at the country’s level have been replaced by calibration of weights at the voivodship level, which ensures better consistency of the obtained results with the demographic data at the voivodship level. Weights’ calculation took into the account the hitherto applied demographic categories by sex, age groups, and place of residence (urban/rural), whereas response rates used for the correction of weights respective to lack of responses have been calculated at the voivodship level since the first quarter of 2016. The appliance of a new method improves precision indices for estimates at the voivodship level, although it may influence lack of full data comparability at voivodships level with the previous periods.