“…Employment by economic activity refers to the distribution of economically active children by the major industrial categories (ISIC revision 2 or revision 3). Manufacturing corresponds to division 3 (ISIC revision 2) or category D (ISIC revision 3). Economically active children refer to children involved in economic activity for at least one hour in the reference week of the survey.
Data are from household surveys by the International Labor Organization (ILO), the United Nations Children’s Fund (UNICEF), the World Bank, and national statistical offices. The surveys yield data on education, employment, health, expenditure, and consumption indicators related to children’s work. Household survey data generally include information on work type – for example, whether a child is working for payment in cash or in kind or is involved in unpaid work, working for someone who is not a member of the household, or involved in any type of family work (on the farm or in a business). Although efforts are made to harmonize the definition of employment and the questions on employment in survey questionnaires, significant differences remain in the survey instruments that collect data on children in employment and in the sampling design underlying the surveys. Differences exist not only across different household surveys in the same country but also across the same type of survey carried out in different countries, so estimates of working children are not fully comparable across countries.
The time series may not be comparable across countries and over time due to differences in survey instruments and survey type…” (Source: World Bank, Understanding Children’s Work project based on data from ILO, UNICEF and the World Bank)