Using Preferred Terms in Indexes
Sciences In science indexes, the preferred subject term for a plant or animal is usually the scientific classification (Genus and species) . There are reference books with these terms (which often are in Latin), but you might also try your search in English (or whatever language is easiest for you) and see if there are any items on your topic. If there are, look in the subject field for the term or terms used in the database and do another search with the preferred term. Plant example In AGRICOLA, a search for carnations finds among the 719 results the following article:Title: Pre-storage low relative humidity treatment for the reduction of fungal populations on the perianth surface of cut carnations.
Author: Fujiwara, K.; Watanabe, K.; Iimoto, M.
Source: Acta horticulturae, 2006 Jan., no. 699, p. 197-203.
When you look in the DE (Descriptors) field, you see the following:
relative humidity; postharvest systems; fungi; Dianthus caryophyllus; cut flowers
A new search for "dianthus caryophyllus" identifies 1477 records. If you plan on narrowing your search to something specific, such as "fungi," you will get better results with dianthus caryophyllus than with carnations. In this instance, with dianthus caryophyllus you find 32 records instead of 5--more than six times the number of items. The differences may not always be this dramatic, but it is always a good idea to do your search with the preferred term.
| Search | Results (Nov. 13, 2006) |
| carnations | 719 |
| dianthus caryophyllus | 1477 |
| carnations and fungi | 5 |
| dianthus caryophyllus and fungi | 32 |
[Note: carnation (no "s") finds 2185 records, but when it is combined with fungi only finds 11 records. Relevancy will remain much higher using the Latin term.]
Animal example When doing research on conservation of the gray wolf, it is better to search for "Canis lupus." A search in Biological Abstracts locates:| Biological Abstracts 1969- | Nov. 13, 2006 |
| gray wolf | 242 |
| gray wol* | 244 |
| Canis lupus | 1120 |
| conservation | 194,197 |
| (gray wolf or gray wol*) and conservation | 122 |
| Canis lupus and conservation | 429 |
This example also shows how the preferred term can make a difference in the number of items identified.
Summary
These are just a few examples showing the importance of using preferred subject headings. However, not every database has subject indexing. For example, ArticleFirst has keyword searching only so if the title of an article, author, publisher, or source does not use the words you type for your search, you will not find that item. Most indexes do use subject terms. See example from SAGE.