Document type assignment accuracy in the journal citation index data of Web of Science

This article reports the results of a study of the correctness of document type assignments in the commercial citation index database Web of Science (SCIE, SSCI, AHCI collections). The document type assignments for publication records are compared to those given on the official journal websites or in the publication full-texts for a random sample of 791 Web of Science records across the four document type categories articles, letters, reviews and others, according to the definitions of WoS. The proportion of incorrect assignments across document types and its influence on document specific normalized citations scores are analysed. It is found that document type data is correct in 94% of records. Further analyses show that within records of one document type as assigned in the data source, the records assigned to the type correctly and incorrectly have different average page counts and reference counts.