The dataset on the distribution of the employed population by hours of work was compiled from an ILO ad hoc inquiry to national statistical agencies around the world which was undertaken in 2005 in order to support various statistical activities, including:

• ILO statistical initiatives for measuring decent work (http://www.ilo.org/public/english/bureau/integration/indicato/index.htm)
• The ILO global report on working time, entitled Working Time Around the World: Trends in working hours, laws and policies in a global comparative perspective (Sangheon Lee, Deirdre McCann, and Jon Messenger, 2007, Routledge and ILO) (http://www.ilo.org/public/english/support/publ/xtextem.htm#b3111)
• ILO work relating to the revision of current standards on working time, adopted by the 10^th International Conference of Labour Statisticians in October 1962 (http://www.ilo.org/public/english/bureau/stat/download/res/hours.pdf)

National statistical agencies were requested to report on the number of the employed population according to their weekly working hours for paid and self-employment separately. They were provided with a standard reporting form to facilitate and standardize the results to the extent possible (questionnaire). A set of specific guidelines on preferred responses was also provided regarding:

Data source: Household-based labour force surveys.

Period covered: (i) The most recent year for which these data are available, (ii) For a year as close as possible to 1995, and (iii) A year as close as possible to 2000, in order to make comparisons over time possible.

Employment status: Separate data for paid employees and for the self-employed (as defined in the International Classification of Status in Employment ICSE-93).

• Paid employees: Workers who hold explicit (written or oral) or implicit employment contracts which provide a basic remuneration that is not directly dependent on the revenue of the unit for which they work.  Some of the tools, equipment, systems or premises that they use may be owned by others, and they may work under the direct supervision of, or according to strict guidelines set by the owners or persons in the owners’ employment.
• Self-employed:  All other workers, including employers, contributing family workers, own account workers, members of producer cooperatives, etc., who hold jobs where the remuneration is directly dependent upon the profits (or the potential for profits) derived from the goods and services produced and who make the operational decisions affecting the enterprise or delegate such decisions while retaining responsibility of the welfare of the enterprise.

Age groups: Data for youth (aged 15 to 24 years) separately from adults (aged 25 years or more), where possible,

Working-hour bands: 1-14 hours, 15-24 hours, 25-34 hours, 35 hours, 36-39 hours, 40 hours, 41-47 hours, 48 hours, 49-59 hours and 60 hours or more. This breakdown is more detailed than that illustrated in the "Resolution concerning statistics of hours of work" adopted by the tenth International Conference of Labour Statisticians (1962, Paragraph 16). However, if they did not have statistics matching the exact ranges shown in the proposed table, national statistical agencies were asked to provide data on distributions as close as possible to the proposed one.

Concepts of working-hour data: Usual hours of work in (i) the main job and (ii) in all jobs, where the information was available. In case data on usual hours of work were not available, actual hours of work was requested. The concept usual hours of work differs from that of actual hours of work, in that the usual hours of work refers to the typical number of hours over a reference period rather than to the exact hours in a specified reference period as is the case of actual hours worked. Usual hours of work per week in a given job may be defined as the hours worked during a typical week in that job for a short or longer period such as a year or a season. The concept of usual hours of work applies both to persons at work and to persons temporarily absent from work. It is equivalent to the normal hours of work plus usual overtime minus usual absence from work. Usual hours of work generally applies to persons in groups of jobs such as self-employed jobs and to certain jobs within unpaid care work where employment contracts stating expected number of working hours are uncommon.

The actual hours of work during a week are the hours that persons in paid or self employment spend on work activities during a reference week. As currently defined, actual hours of work should include: (a) all hours spent on work activities, whether at the place of work or not, including work done at home and travelling time required by the job; (b) all hours worked as overtime, whether paid or unpaid; (c) all hours spent on work such as the preparation of the workplace, repairs and maintenance, preparation and cleaning of tools or work processes; (d) all hours spent waiting or standing by for such reasons as lack of supply of work, breakdowns of machinery, or accidents, or time spent at the place of work during which no work is done but for which employees are paid under a guaranteed employment contract; (e) all hours corresponding to short rest periods at the workplace, including tea and coffee breaks. Actual hours of work should exclude: (f) hours paid for but not worked, such as paid annual leave, paid public holidays, paid sick leave; (g) meal breaks; (h) time spent on travel from home to work and vice versa.

Source and coverage: The type of source and its exact title , as well as the name of the publication or website address in which the statistics appear. The statistics for both sexes should be annual averages and cover the whole country, all economic activities and all sectors of the economy, to the extent possible.

The 2005 ad hoc inquiry presents a global attempt to establish a comparable data set on distributions of the employed population by hours of work, covering a total of 55 countries in different regions. However, due to considerable variations in reported data in terms of covered period, working-hour bands, age groups etc., great care should be taken when attempting cross-countries comparisons.