Scientific information retrieval usually starts with defining the research area of the work at hand, whether it is an essay or some other form of assignment. The starting point for you is to consider the terminology and the interrelationships between terms in your field. You may even draw a chart of the concepts and key words that you can think of (a concept chart).
Raymond has to write an essay on the health effects of chocolate. He asks his friend Alisa to help him; after all, she is known for her good argumentation skills and her love of chocolate. After reading a few articles they found on Google Scholar, they summarise the central concepts related to the topic in a diagram suitable for the essay. During their work, they make use of two bars of chocolate of a brand that Alisa recommends.
From concept to search words
When you have found the concepts that describe your research area best, you can use them as search words. In addition to the words you come up with yourself, you can look for more terms in e.g. dictionaries and encyclopaedias, articles and textbooks. You can also use personal and geographical names as search words.
When you know what it is that you want to find, try to put it as clearly as you can to the search engine or database you are using. The default for many databases is keyword search with any words in a natural language as search words. The result of a word search may be very extensive, since the search will look for the word in all fields of the reference records. Before starting your search, it is recommended that you read the database-specific instructions.
Subject headings and thesauruses
Subject heading (or descriptor) is a term used in databases and library collections to describe the main contents of publications.
A thesaurus is a list of subject headings that gives those who store data and those who seek it a common language; with the help of a thesaurus, it is easier to find information. One thesaurus may be used in one or several databases. You can utilize both general and specialized thesauruses:
Thesauruses often describe the relations between subject headings. This feature can be used to your advantage in the planning phase of your information retrieval. You will find a word and its broader, narrower and related terms in the thesaurus hierarchy. Thesauruses often indicate which of the subject headings is recommended (for example ‘Instead of this term use:’). The images below show examples from the General Finnish Ontology (YSO): the findings on the hierarchical relationships on keywords “cat” and “copyright”.
A subject heading search will give you a more specific result. This kind of search will only be directed at the subject heading field. Another advantage is that multi-language sources will be included in the result without separate searches. The advantages with subject headings are most obvious when using international databases, where varying terms may be used, but please note that a mere subject heading search may limit the result too much. You can use subject heading terms in a free search as well. Before starting a search, you should check that the word that you propose to use qualifies as a subject heading in the database you are using.Databases use different subject heading vocabularies, such as LCSH, MESH and YSO. Finnish libraries add keywords to databases from the General Finnish Ontology (YSO). When searching in, for example, Helka or Finna.fi, you can use YSO to find keywords.