occupational classification The smallest unit of an occupational classification is the concept of a job, defined as a set of tasks to be performed by an individual, and commonly identified by a job title. Occupation is often synonymous with job but may refer to a group of similar jobs identified with a common occupational title. Jobs and occupations can be described not only in terms of tasks, but also in terms of associated characteristics such as skill, responsibility, earnings, entry qualifications, and prestige (see STATUS). More diffuse characteristics may derive from the incumbents of occupations, such as life-style, cultural mannerisms, and so forth.

Occupational classifications are essentially ways of grouping and ranking jobs and occupations. Systems of classification vary according to which criteria are given priority during the exercise, and these may differ depending upon the purpose of the intended analysis, and the theoretical framework deployed. Most classifications are developed by national census offices for the production of national employment data, the most common classification being the International Standard Classification of Occupations (ISCO) developed by the International Labour Organization, of which there are now several versions distinguished by their year of first publication (hence the ‘ISCO-68’ and ‘ISCO-88’ classifications). The latest (1988) classification is based on the concepts of job (‘the set of tasks and duties executed’) and skill (both in terms of skill level, or ‘the complexity and range of the tasks and duties involved’, and skill specialization, defined by ‘the field of knowledge required, the tools and machinery used, the materials worked on or with, as well as the kinds of goods and services produced’). This yields a pyramid whose hierarchical structure consists of ten major groups, at the top level of aggregation, subdivided into 28 sub-major groups, 116 minor groups, and 390 unit groups. Thus, for example, within major group 4 (clerks), sub-major group 41 is office clerks, which includes minor group 412 (numerical clerks), comprising the two unit groups 4,121 (accounting and book-keeping clerks) and 4,122 (statistical and finance clerks). The US Census Bureau and UK Office of National Statistics produce their own—rather different—classifications.

In sociology, occupational data are commonly used for the analysis of status attainment and occupational mobility, so consistent criteria of classification and a hierarchical arrangement of grouped data are sometimes considered important. Class theorists who focus on work situation and market situation favour classifications of occupations based on sources and levels of income, employment status, or conditions of employment, the best example being the Goldthorpe Classes (referred to in some countries as the Erikson–Goldthorpe–Portocarero Classes), which are derived in the British case from the UK census office classification of occupations and employment statuses (see R. Erikson and and J. H. Goldthorpe , The Constant Flux, 1992
). Those who equate social class with social status have often used subjective assessments of occupational prestige as the basis of class standing, as for example in the Hope—Goldthorpe Scale of Occupational Prestige (see J. H. Goldthorpe and and K. Hope , The social Grading of Occupations, 1974
).

Most occupational classifications are said to embody a male bias, reflected in the way occupations are distinguished, grouped, and ranked. Occupations filled largely by women are frequently grouped together at a very low level of aggregation (as, for example, in the case of clerical occupations) so that they cannot subsequently be disaggregated and relocated as circumstances change. Similarly, the skill and status level of occupations dominated by women may be underestimated, possibly distorting the location of such occupations in some subsequent derived status classifications.

Social and economic change continually modifies the occupational structure and limits the capacity of any particular classification to reflect this structure over time. Continual updating is therefore necessary, although this then further complicates the process of identifying changes in the occupational structure over time, since some of these may simply be artefacts of the changing classification itself.