Effect of main headings and qualifiers on manual searching in printed subject index

A series of manual search are made on pairs of main heading and qualifier as well as main headings only in the subject indices to the INIS Atomindex. The former searching method is capable of achieving the recall ratio of 10 to 40% at the precision ratio of 45 to 20% in shorter searching time than the latter on an average. The latter can yield the recall ratio of 45 to 70% at the precision ratio of 20 to 5% in shorter searching time than the former on an average. These results are compared with statistics of practical flagging to the data base. Such a two-level flagging system is superior to the subject index system structured from single-term subject headings using descriptors in a thesaurus. It would also lead to higher recall ratio in shorter searching time by labelling to a document two main headings and two qualifiers to a main heading at a minimum but by limiting a label of over seven main headings. (author)