Major Groups and Skill Levels
ISCO 88 Guide Section 2
Skill levels, formal education, training and experience
The use of ISCED to define skill levels does not mean that skills can only be obtained by formal education or training. Most skills may, and often are, acquired through experience and through informal training, although formal training plays a larger role in some countries than in others and a larger role at the higher skill levels than at the lower. For the purpose of the ISCO classification system, the decisive factor for determining how an occupation should be classified is the nature of the skills that are required to carry out the tasks and duties of the corresponding jobs - not the way these skills are acquired.
'Skill specialisation' is related to subject matter areas, production processes, equipment used, materials worked with, products and services produced, etc. Therefore words describing subject matter, production processes, etc. have to be used as labels for the core sets of skills with which occupations are concerned.
Classification Structure
ISCO-88 defines four levels of aggregation, consisting of:
10 major groups
28 sub-major groups (subdivisions of major groups)
116 minor groups (subdivisions of sub-major groups)
390 unit groups (subdivisions of minor groups)
Many users of the 1968 ISCO found that its top aggregation level of nine groups meant that the differences within each group were too large for the groups to be useful for description and analysis. However, the next level of aggregation, with 83 groups, represented too much detail for many types of analysis, as well as for international reporting of occupational distributions, especially if the data are obtained through sample surveys. ISCO-88 therefore includes the 'sub-major groups' as a new level in the aggregation system - between the major and minor groups.
Unit groups in most cases will consist of a number of detailed occupations. For example, as a separate occupation nuclear physicist belongs to ISCO-88 unit group 2111 Physicists and astronomers, which belongs to minor group 211 Physicists, chemists and related professionals, which is part of sub-major group 21 Physical, mathematical and engineering science professionals of the major group 2 Professionals. The major group structure of ISCO-88 is shown below in Table 1.
Table 1: ISCO-88 major groups and skill level
Major group ISCO skill level
1 Legislators, senior officials and managers -
2 Professionals 4th
3 Technicians and associate professionals 3rd
4 Clerks 2nd
5 Service workers and shop and market sales workers 2nd
6 Skill agricultural and fishery workers 2nd
7 Craft and related workers 2nd
8 Plant and machine operators and assemblers 2nd
9 Elementary occupations 1st
0 Armed forces -
Eight of the ten ISCO-88 major groups are delineated with reference to four broad skill levels. These four ISCO skill levels have been defined in terms of the educational levels and categories of the International Standard Classification of Education (ISCED). Five of the eight major groups, i.e. 4, 5,6, 7 and 8 are considered to be at the same skill level and are distinguished by reference to broad skill specialisation groups. Skill level references are not made in the definitions of two major groups (Legislators, senior officials and managers and Armed forces), because other aspects of the type of work were considered more important as similarity criteria, i.e. policy making and management functions, and military duties, respectively. As a result there are significant skill level differences within each of these two major groups. However, the sub-major and minor groups of major group 1 have been designed to include occupations at similar skill levels.
Administrative and managerial occupations
All occupations which consist of jobs in which the workers have mainly legislative, administrative or managerial tasks and duties should be classified to major group 1 'Legislators, senior officials and managers'. In ISCO-68 they were partly classified to major group 2 (Administrative and Managerial Workers) and partly to other major groups.
'Working proprietors' are to be classified according to whether their tasks and duties are mainly similar to those of managers and supervisors or to those of other workers in the same area of work. This is because the status of 'working proprietor' is seen as related not to type of work performed but to 'status in employment' - corresponding to the 'self-employed' and 'employer' categories of the International Classification of Status in Employment (ISCE). One self-employed plumber may have mainly managerial tasks but another may do mainly the same work as a salaried plumber, depending for example on the size of the firm. In the former case the job should be classified with managers and in the latter case with plumbers.
'Craft' occupations and 'operative' occupations
To cope with the issue of different skill requirements for jobs with similar purposes due to difference in technologies used, a distinction is made at the major group level between occupations that are essentially craft-oriented, and occupations that are essentially oriented towards the operation of tools, machinery and industrial plants.
Occupations which are craft oriented consist of skilled jobs directly involved in the production of goods where the tasks and duties require an understanding of and experience with the natural resources and raw materials used and how to achieve the desired techniques and practices, but they may also use more technologically advanced tools and machines, provided that this does not change the basic skills and understanding required. Modern machines and tools may be used to reduce the amount of physical effort and/or time required for specific tasks, or to increase the quality of the products. The tasks and duties of jobs in occupations which are oriented towards the operation of tools, machinery and industrial plants require an understanding of what to do with the machines to make them work properly, of how to identify malfunctioning and of what to do when something goes wrong. The skills required are oriented towards the machines and what they are doing rather than to the transformation process or its results. Occupations where the tasks and duties consist of assembling products from component parts according to strict rules and procedures are considered to belong to the same major group as the machine-oriented occupations. Jobs which only require low or elementary skills and little or no judgement are classified to occupations in major group 9.
Armed Forces
As in ISCO-68, jobs in the armed forces should be classified in a separate major group 0 'Armed forces', even if the jobs involve tasks and duties similar to those of civilian counterparts.
Apprentices and trainees
Both 'apprentices' and 'trainees' should be classified according to their actual tasks and duties as, if needed, these two groups may be separately identified through the 'status in employment' classification. ISCO-68 recommended that apprentices should be classified to the occupation for which they are being trained, but that trainees be classified according to their actual tasks and duties.
Classifying 'multiple' jobs
The problem of classifying jobs which have a broad range of tasks and duties should be handled by the application of some priority rules. i.e. some tasks and duties are given priority in determining the occupational category to which a job should be classified, such as:
(a) in cases where the tasks and duties are associated with different stages of the process of process of producing and distributing goods and services, the tasks and duties related to the production stages should take priority over associated tasks and duties, such as those related to the sale and marketing of the same goods, their transportation or the management of the production process (unless either of these tasks and duties dominates). For example, the worker who bakes bread and pastries and then sells them should be classified as 'baker', not as 'sales assistant'; the worker who operates a particular type of machinery and also instructs new workers in how to operate the machine should be classified with the machine operators; the taxi driver who drives his/her own car and also keeps the accounts should be classified with motor-vehicle drivers; and
(b) in cases where the tasks and duties performed require skills usually obtained through different levels of training and experience, jobs should be classified in accordance with those tasks and duties which require the highest level of skill. For example: there are a number of jobs whose tasks and duties most of the time require a set of relatively easily obtained skills, and where the workers are also expected to have skills which require more training or experience which enables them to cope with unexpected and infrequent situations, for instance, to avoid accidents or injuries.
It is recognised that a certain amount of judgement and adjustment to national circumstances will be necessary in the choice and application of these priority rules.