Restructuring a thesaurus: the case of the Education, Skills and Children's Services Thesaurus

Suzanne Barbalet

Some weeks ago I visited the offices of the Department for Education (DfE), Westminster to gain a snapshot view of innovative work being undertaken there to revise the in-house thesaurus: the Education, Skills and Children’s Services Thesaurus (ESCS).

Like HASSET it is approximately thirty years old and was first constructed in the 1980’s by Jean Aitchison who designed the UNESCO Thesaurus which HASSET was modelled upon. Until HASSET became a thesaurus in its own right the UNESCO thesaurus was the source of HASSET and, by default, ELSST terms.

Jean Aitchison used the Bliss Classification Scheme to establish the core framework of ESCS. Since then it has been continually updated. Thus the thesaurus evolved into an essential retrieval tool to access the contents of the then DfE’s previous website; being the browse tool for education.gov.uk.

ESCS proved to be so valuable and reliable in that task that when GOV.UK became the website through which all departmental information was accessed some of the earlier functions of the ESCS thesaurus were greatly missed by DfE staff. While ESCS provided core education subject categories for GOV.UK once converted to subject categories the granular search functions that ESCS offered as a browse tool were lost. Like all pre-defined “controlled vocabularies”, while providing users with a quick and easily navigated search base, subject categories are less flexible to update and refine by users to retrieve information with as high a level of accuracy as thesauri. Thus DfE staff requested the librarian to undertake the legacy work necessary to make the ESCS thesaurus function again as an internal indexing and information retrieval tool.

By establishing and selecting index terms using a ‘concept analysis’ approach, ambiguity in ESCS was controlled and the thesaurus was once again supplied with new topics that reflected departmental responsibilities. Departmental staff members were then re-trained to apply thesaurus concepts for a number of key knowledge organization tasks. One such task was to link external correspondence to a department specialist. For example, an external item of correspondence that may have reported an incident of a pupil wearing jewellery at school would be indexed with the concept SCHOOL UNIFORMS and matched with keywords on a staff member’s SharePoint page so that the correspondence was instantly accessed by the appropriate staff member.

It was also to be used to satisfy internal demand for information access. Workshops were set up to review and collate all prospective terms currently used within the department to tag information. Controlled lists were brought together and reviewed in these workshops. By constructing a live thesaurus in line with indexing needs a current and logical structure was imposed and the new concepts were integrated into the old ESCS thesaurus. It is a challenging task and not only are the results of the work on the evolving thesaurus structure impressive, but so too is the level of cooperation and support within the department for this project.

The decisions to be made are not too dissimilar to the consistency work undertaken for the CESSDA-ELSST project. For CESSDA-ELSST we brought together two thesauri with different structures and made all terms and structures consistent where different indexing practices had caused them to diverge. It is not an easy task structurally but there is much to be learned from similar exercises and much we can contribute to the KOS community as a result of our experience. The importance of choosing labels that work well structurally is a key element in the work in both cases.

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