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. The survey methodology has been changed since the fourth quarter of 1999. The observation of the selected week in the middle month of a quarter was replaced with the method of the continuous observation (mobile survey week) allowing presentation the situation on the labour market during the entire quarter. 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 2020 this are figures below 10 thousand. Annual averages - concern population aged 15 years and more according to the actual place of residence. Valid in years: 1995-2011. Beginning in 2015 the data included precision index.Precision index or precision of an estimator of some variable (e.g. global value of some parameter in a surveyed population) is defined as the relative standard error of this estimator or otherwise its coefficient of variation. In case of the Labour Force Survey (LFS), economic activity is assessed on the basis of the situation in the reference week. Economic activity of population is used to determine the status of the population (aged 15 years and more) on the labour market. As regard economic activity, the population is divided into categories: the employed, the unemployed and the economically inactive. Populations of the employed and the unemployed create the economically active population. Presentation of the data according to the above-mentioned categories includes also more detailed division, i.e. by age.