The occupations and industry groups covered comprise, as far as possible, those which are important in terms of the number of persons employed in them, those which fall within the scope of the ILO Industrial Committees and similar bodies and those which are important in terms of employment of certain types of workers (such as women, salaried employees and so on). The food items covered are, to the extent possible, representative of the dietary habits in countries throughout the world. In order to take account of the differences between countries, the selection of occupations and items for coverage in the Inquiry is necessarily extensive. It is evident that not all of them are relevant to all countries.
The Inquiry is conducted with reference to the month of October each year, by means of two questionnaires, one relating to wages and hours of work and the other to retail prices. These contain brief instructions for their completion , together with specifications of the types of data sought. Two annexes which accompany the forms provide detailed descriptions of the occupations and food items covered. Their aim is to help respondents to identify the respective occupations and items, thereby enhancing the comparability and continuity of the survey results. The questionnaires are sent to governments for transmission to the relevant reporting agencies, which are requested to supply information for as many of the occupations and items as possible. The Office does not ask or expect reporting agencies to conduct special surveys in order to complete the questionnaires, but to supply whatever relevant information is already available. In the case of wages and hours of work, a number of sources are commonly used, including regular surveys such as occupational wage surveys, administrative records of wagefixing bodies, laws or regulations. In general, the retail prices are those collected for the purposes of calculating consumer price indices. Some countries, however, do carry out special data collection in order to complete the forms.
The survey results are published without adjustment, except in the case of retail prices when some conversions are necessary in order to be able to publish prices for standard quantities. Care should be taken when using and interpreting the results, particularly for making international comparisons. Despite efforts to promote the comparability and continuity of the data, there are some unavoidable differences between the concepts used, specifications of occupations and items, reference periods, types of sources and methods of data collection in the various countries. As much information as possible is provided in the tables in the form of footnotes, and this should be taken into consideration by users.