SEARCH TECHNIQUES

There are several ways to make the search more precise and get more useful results. The search can be limited to certain fields, search terms truncated, the search refined and search terms combined to form different kinds of search queries. Different databases have different kind of search options. This chapter concentrates on introducing the most common search techniques, which can vary according to the database. Therefore, before you begin the search, you should always remember to check the kinds of search techniques the database supports.

BROWSING / SEARCH

Browsing is going through a list, usually in alphabetical order (e.g. authors, titles, key words). A search retrieves all the references to records which contain the search term.

TARGET OF THE SEARCH

Databases often have basic and advanced search possibilities. In basic search, the search is directed by default to certain fields in the records, which have been added to the database (e.g. free text based search). Advanced search includes other limiters and features for more complex searches, which will help to refine the search.

FREE TEXT BASED SEARCH

In free text based search the information seeker chooses search terms which may be found anywhere; the title of the publication, keywords, abstracts or in the text itself. Furthermore, the search expressions do not have to be in one language only, if the search is conducted in a database containing material in several languages.

Free text based search comes most useful in the first stage of a systematic search. It is also useful, when the field of research is new and does not have a well-established terminology, or when the topic of the search is very specific. When you have retrieved one or more relevant books or articles, you may use the keywords and subject headings the record has in new searches.

SUBJECT HEADING SEARCH

Free text based search may often retrieve plenty of irrelevant results. The larger the database and the more extensive the topic of the search is, the more difficult it is to achieve relevant search results with the free text based search.

The local catalogues of libraries and many of the larger databases add subject headings to the records of the publications. Subject headings are descriptors, describing the contents of that publication as exactly as possible. Searches, which have been conducted with the terms chosen from thesauri or controlled vocabularies, more often than not, give more relevant results than free text based searches. Subject heading searches can be either restricted to subject heading field, or the search may be conducted on all search fields.

International databases often have thesauri, which have been developed particularly for those databases. For instance, ERIC, the database for education related literature, has its own thesaurus where you may search for English terms used in education sciences.

LIMITING THE SEARCH TO OTHER FIELDS

If the free text based search retrieves too many records, and the subject heading search too few, you may try to limit the search to other fields, such as abstract. It is also possible to limit the search according to the type of the publication, for example, in Tamcat, it is possible to search only theses.

BOOLEAN SEARCH

Boolean search is an integral part of information retrieval, since it enables the user to construct logical relationships between search terms. When one search term does not describe sufficiently the topic, you should use several words and connect them with Boolean operators. The most common operators are AND, OR and NOT.

AND: (A and B) e.g. literature AND teaching

• use AND if you want references including all the search terms
• the operator AND limits the search results

OR: (A or B) e.g. "preschool education" OR "elementary instruction"

• use OR if you want references including any one of the search terms
• most commonly used when the search terms are synonymous or they are the same in different languages
• the operator OR expands the search results

NOT: (A not B) e.g. philology NOT Nordic

• use NOT if you want to exclude a certain part from the search results
• the operator NOT limits the search results
• you should be careful when using this operator: you may accidentally exclude relevant material from the results.

The same query may include more than two expressions and several Boolean operators. In such cases parentheses are used to force the order of the search process; the entries surrounded by the parentheses are conducted first. For instance: (women OR gender) AND (education OR profession).

TRUNCATION

If you are conducting a search in a language, which is extensively inflected, such as Finnish, it is recommended to use truncation. Thus the search will retrieve all the different forms of the search term. Truncation marks vary between databases; usually it is either '*' or '?'.  

For example,

• 'school*' will retrieve school, schools, schooling
• 'litera*' will retrieve literature, literary, literal, literally, literarily, literacy

Truncation may be used at the beginning, middle or end of the word. In addition, some databases allow the use of wildcard search, that is, substituting one or more characters inside the word.

• te*ts will retrieve texts, tents, tests
• analy*e will retrieve analyze, analyse

PHRASE SEARCH

Different databases have different kinds of techniques for building a phrase. In some databases the phrase is formulated by just typing the words one after another, in others the phrase has to be enclosed in quotation marks (e.g. "French Revolution" or "Finnish language"). Truncation within the phrase may also be possible.

LIMITING THE SEARCH RESULTS

In some databases the search can be limited by, for example, the date, language, or type of the publication. Limiting might come in useful, if the search results are too large or if the user wants sources in a certain language.

OTHER SEARCH TECHNIQUES

There are other kinds of search techniques besides the above-mentioned ones, such as fuzzy search, which retrieves words resembling the search terms. If the search result does not include any of the words from the submitted query, it is possible that the search engine supports this kind of automatic technique.

SEARCH RESULT

Search results may appear in a different order depending on the chosen search technique. In browsing mode, the search results display a list that may be browsed, whereas in searching mode the results may be organised, for example, according to relevance, or in alphabetical or in chronological order.