As regards the most recent surveys (from 1993), the information is distributed in the Annual database practically in full (also including data found in the monographic sections of the individual surveys). Only information that could lead indirectly to the identification of the respondents is excluded.
The documentation on the structure of the archives and questionnaire used is provided separately for each year.
Data from 1977 are contained in the Historical database but only include the subsets of variables considered useful for longitudinal analyses. The new unit weighting coefficients are also available; these should limit the impact of differences in survey procedures on the results.
Because of the different weights and other processing of the data, the results obtained from information contained in the historical database may not tally with results obtained using data published in the annual databases in relation to the same years.
The methodological notes summarize the main methodologies used in the survey, particularly those relating to the statistical processes and data handling.