An index is an alphabetically arranged list of all keywords that can be found on one field of the database. Indexes can be browsed and suitable search words can be chosen. Usually, the search can be performed by clicking on the index entry or by selecting it. When selecting several entries, pay attention to the operator that connects them (the operator can be changed).
Indexes are helpful when you are not sure of the spelling of a word.
Author index contains the names of the authors in alphabetic order; it can be browsed to find out the spelling of the name or to check the initials of the author’s first names. Clicking on the name(s) in the index, you can find all the works of an author in the database.
E.G., the EBSCO database Academic Search Complete has an index of geographic terms; choosing Estonia, you will get articles about Estonia.
Subject heading or descriptor is a word used for describing documents in databases. This involves a controlled vocabulary, meaning that the content of the document cannot be described with any words, but the terms are chosen from a standardised list. One word has been selected to express a notion, and all documents of similar content can be retrieved by searching with this word. The very word that forms the subject heading may even not be present in the text.
Subject headings can be browsed in the subject heading list or thesaurus. The thesaurus is an ordered list of subject headings.
Compared with the subject heading index, the thesaurus reveals semantic connections between subject headings (narrow terms, wider terms, related terms) and is a helpful tool in finding possible search terms.
Not all databases (e.g. Web of Science, publishers’ databases) include a subject index or a thesaurus, but they can surely be found in subject databases.
Find the subject index or thesaurus of the database (usually called Subjects, Subject Terms or Thesaurus).
In order to browse it, enter the word you want to check up on the field Browse. Usually, the subject headings can be browsed in alphabetic order and, as a subject heading may contain several words (e.g. educational psychology), the index can be browsed by words included in a subject heading.
Choose a suitable subject heading and perform the search. You can use several subject headings and connect them with operators AND or OR.
When you use words from the subject index, you can be sure to find all documents that have been described by this word or phrase.
In order to get the same result with the key word search, you have to search with all possible synonyms that can be used for the term you need, and take into account different spellings and forms of the singular and plural.
Use the indexes and the thesaurus or subject index in cases you cannot get relevant results with the key word search or if you want to be sure that you have found all documents concerning your subject.