The following international standards for coding and classification were used:
- economic activity (the sector in which the respondent works): coded according to NACE Rev.1.1, 2-digit version
- occupation: recorded verbatim and coded according to ISCO 88 (COM)
- education: coded according to modified version of ISCED-97
Sector
| Section | Sub-section | Economic activity | No. of Digits |
|---|---|---|---|
| A, B | agriculture, hunting and forestry + fishing | 1 digit | |
| C | mining and quarrying | 1 digit | |
| D | manufacturing | 2 digits | |
| 15+16 | food products, beverages and tobacco | ||
| 17+18+19 | textiles, clothing and leather | ||
| 20+21 | wood industry, paper | ||
| 22 | publishing, printing | ||
| 23+24+25+26 | chemical, rubber, mineral | ||
| 27+28+29+30 | metal products and machinery | ||
| 31+32+33 | electrical and electronics, precision instruments | ||
| 34+35 | automobile and other transport equipment | ||
| 36 | furniture | ||
| E | electricity, gas and water supply | 1 digit | |
| F | Construction | 1 digit | |
| G | wholesale and retail trade, repair of motor vehicles, motorcycles and personal and household goods | 1 digit | |
| H | hotels and restaurants | 1 digit | |
| I | transport, storage and communication | 2 digits | |
| | 60 | land transport | |
| | 61+62+63 | water,air sampling activities | |
| | 64 | post and telecommunications | |
| J | | financial intermediation | 2 digits |
| | 65+67 | financial intermediation and auxiliary activities | |
| & | 66 | insurance | |
| K | real estate, renting and business activities | 1 digit | |
| L | public administration and defence, compulsory social security | 1 digit | |
| M | education | 1 digit | |
| N | health and social work | 1 digit | |
| O | other community, social and personal service activities | 1 digit | |
| P+Q | private households with employed persons, extra-territorial organisations and bodies | 1 digit |
Occupation
| 1 | Legislators, senior officials and managers | (1 digit) |
| 2 | Professionals | (1 digit) |
| 3 | Technicians and associate professionals | (1 digit) |
| 4 | Clerks | (1 digit) |
| 5 | Service workers and shop and market sales workers | (1 digit) |
| 6 | Skilled agricultural and fishery workers | (1 digit) |
| 7 | Craft and related trades workers | (1 digit) |
| 8 | Plant and machine operators and assemblers | (1 digit) |
| 9 | Elementary occupations | (1 digit) |
| 10 | Armed forces | (1 digit) |
The type of occupation is defined according to the International Standard Classification of Occupations, ISCO-88, 1-digit level. In the survey, four categories of employees are distinguished:
- high skilled white collar (ISCO codes 1,2 and 3) includes legislators, senior officials and managers, professionals and technicians and associate professionals;
- low skilled white collar (ISCO codes 4 and 5) includes clerks and service workers and shop and market sales workers;
- high skilled blue collar (ISCO codes 6 and 7) includes skilled agricultural and fishery workers and craft and related trades workers;
- low skilled blue collar (ISCO codes 8 and 9) includes plant and machine operators and assemblers and elementary occupations.
Armed forces are excluded.
Education
The respondents were divided into 6 categories of educational level, based on an adapted version of ISCED-97:
| no education | ISCED 0 |
| primary education | ISCED 1 |
| lower secondary education | ISCED 2 |
| higher secondary education | ISCED 3 |
| post-secondary non-tertiary education | ISCED 4 |
| university degree | ISCED 5 |
| postgraduate studies | ISCED 6 |