1. Overview

Standard Occupational Classification (SOC) 2020 Volume 1 contains the framework structure for four-digit SOC, as well as descriptions for each of the nine Major Groups, 26 Sub Major Groups, 91 Minor Groups and 412 Unit Groups identified within.

Some existing users of the SOC felt that the current four-digit structure was not granular enough for their needs. The SOC Extension Project, developed to meet stakeholder needs, has resulted in the addition of a fifth layer to the classification, which comprises of 1,369 Sub Unit Groups (SUGs).

The development of accurate SUG descriptions is essential in enabling both the automatic and manual matching of data. In turn, this is important in realising the long-term goal of statistical production at the extended level.

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2. Challenges in developing Sub Unit Group descriptions

The classifications team were keen to avoid duplication and therefore aimed to base the sub unit group (SUG) descriptions on existing available information. Numerous potential sources were identified from which descriptions could be compiled. These included international classifications such as O*net (United States) and the European Skills, Competencies, Qualifications and Occupations framework (ESCO) career advice websites, job vacancy portals and industry specific organisations.

Despite the wealth of data available, there was no identifiable single source to which all Standard Occupational Classification (SOC) 2020 SUGs could be matched. Taking descriptions from multiple sources risked inconsistencies in the formatting and language used. Furthermore, the description of “job titles” that were found in many of the identified sources rather than “occupation groups” limited the direct transferral of existing descriptions to the extended SOC framework.

As such, it was determined that while information within these existing descriptions could be used to inform the writing of SUG descriptions, these would also require elements of tailoring before adoption as SUG descriptors.

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3. Development process of the Sub Unit Group descriptions

Step 1: Develop a crosswalk to an existing main source

Following a review of the available sources alongside consultation with existing Standard Occupational Classification (SOC) users, it was concluded that the European Skills, Competencies, Qualifications and Occupations framework (ESCO) would provide the most appropriate and complete source for an initial mapping exercise to be conducted.

ESCO contains 2,942 occupation groups making it far more granular than both the current UK version and the experimental extended version of SOC. Linking here enabled SOC to adopt existing descriptions a well as important skills and competencies already available within the European classification.

A manual exercise was undertaken to identify matches between the two classifications. Four-fifths of all Sub Unit Groups (SUGs) (excluding not elsewhere classified (n.e.c.) groups) were able to be mapped to at least one corresponding ESCO group. There were five possible ways in which a SOC to ESCO match could be classified.


No appropriate match could be found with ESCO to match the SUG within SOC.


The SUG was able to be matched to a group in ESCO however the description of the ESCO group only partially covered the SUG.

One to one

A direct match was identified between a SUG and a corresponding occupation group used by ESCO.

One to multiples

There were many instances in which a single SUG was found to map to multiple ESCO groups, because of the greater level of disaggregation found in ESCO.


Refers to those groups within SOC that contain occupations not elsewhere classified within the framework.

Step 2: Identify and fill data gaps

Each of the five mapping types required a slightly different approach.


Identification of an appropriate alternative source(s) from which to adopt a group description. Skills and competencies were also sought from a range of sources.


Identification of an appropriate alternative source(s) to further inform the development of the group description. In these cases, descriptions are likely to become either bespoke or hybrid in nature. Skills and competencies were also enhanced from additional sources.

One to one

Where a straight match to ESCO could be identified, efforts were made to retain the description to as greater degree as possible. This was measured against also ensuring a consistent use of language across the framework. Skills and competencies were also harvested from the ESCO match.

One to multiples

A new description was developed which aimed to merge the identified ESCO groups together. In some instances, the description also required the inclusion of information form additional sources. Skills and competencies were merged from the relevant ESCO groups.


These groups refer to the existing SOC Unit Group descriptions. The often individually distinct set of occupations contains within an n.e.c. group makes description at the extended level problematic. A reverse ESCO to SOC mapping exercise would also be required to identify the ESCO codes to be assigned here.

Other sources that were used for researching and developing the remaining group descriptions, as well as sense checking those adopted from ESCO included:

  • O*net
  • careers advice websites, for example, The National Careers Services (NCS), Prospects, CareerSmart and My World of Work from Skills Development Scotland
  • industry specific websites – examples included police or army roles as well as occupations within the nuclear sector
  • job vacancy portals such as indeed.co.uk, totaljobs.com and ziprecruiter.com

Step 3: Edit and review

Following the development of SUG descriptions, a further editing exercise was undertaken. The purpose of this was to ensure:

  • a commonality of language across the framework; this is particularly necessary to eliminate differences in the language used between O*net and ESCO
  • application of plain English text throughout
  • removal of Americanised spelling from the text
  • standardisation of commonly used terms used throughout grammar check
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