Search techniques

When searching for academic literature, it is common to use a specific search method in order for your reader to follow your search strategy and see how you have valued the different search results.

You can understand which method you should use from your course PM, course assignment, or ask your teacher. The following methods are available:

• Systematic search
• Advanced systematic search
• Structured search
• Chain search/snowball search/unsystematic search

Below is a description of how your search queries can develop your searches with different types of subject headings, search terms, how to use truncation, masking, field and phrase searches, and how to use AND and OR.

Search terms, subject headings and keywords

A search term, sometimes called a free-text word, is any word you can think of. The word you come up with and start searching with without any deeper thought about whether it is a useful word or not.

Subject words are controlled words used by those who enter the articles in the database.

With the help of the subject headings, you can find the articles you are looking for faster. The subject headings are in a hierarchical structure, with broader and narrower words, which when used makes it easier to find relevant articles in the databases.

The articles in the database are tagged with the subject words. If you know hashtags (#study, #nurse, #universitywest...) from, for example, Instagram, subject headings work in the same way, but with the big difference that it is a predetermined list you choose your words from.

What is important to keep in mind is that the newest articles do not have subject headings. Articles are added to the database as soon as they are published, but it can take up to six months before someone has time to read or look over the article and give the proper subject words to the article. This is one reason why we often ask you to use both search terms and subject headings when searching. If you only use subject headings, you risk missing the very latest research in your subject.

What about keywords?

Keywords and subject headings are not the same thing. Keywords are the authors' own words that they give their article based on what it is about. The subject headings are given to the article through the database.

If an article is about cancer and the author gives the article that as a keyword, the article will probably be tagged with the subject word Neoplasm in Cinahl and PubMed as it is the subject word for cancer in these two databases. In another database, the subject word for cancer may be something else.

Truncate

To truncate means to cut off the word you want to search for. Truncate is done in most databases using the asterisk on your keyboard *.

When you truncate a word, the search service or database finds alternative endings for your word. If you search for disabilit* (star) you will get hits for both disability and disabilities. If you search for child* (star), you will get hits for child, children, childrens, childhood and so on.

Be sure to cut the word in a useful place. A search for nurse* does not help much, while a search for nurs* will give you significantly more hits as you get nurse, nurses, nursing in the same hit list.

Truncation is a great way to broaden your search.

Masking

Masking is used when you are uncertain about a the spelling of a word or when you want alternative spellings for a search term. The letters to be masked, i.e. covered, are usually replaced with the question mark, but this may differ in different search services and databases.

The letters in the word that are to be masked are replaced with the question mark (?). An example is wom?n, which can then give hits on woman and women.

If the word had been truncated wom*, we would also have gotten a hit on womb, which we probably weren't looking for in this case.

Field search

Field search means controlling that the search terms should be in a certain field. In the example in the image, we see a number of possibilities for field search:

• Select a field = here you search for your keywords in title, abstract and subject heading. Select a field is usually the default.
• All Text = here you search for your keywords in all indexed fields, i.e. all the information that is available about the article. Please note that it does not search in the article itself.
• AB = here you search for your keywords in the abstracts of the articles.

As you'll see, there are many more choices, but these three are often quite useful.

Phrase search

Phrase search means that the search service or database must search for two or more words in a row. No other word may stand between the words you are searching with. In order for the database to understand this, quotation marks are used around the words that should be next to each other.

Example:

• "Patient experience"
• "Artificial intelligence"
• "Pre School Teacher"

If the quotation marks are not used, the search is made on single words and it then gives a completely different number of hits. A search for "patient experience" and "heart failure" in Google Scholar with a delimitation of the last five years gives me just under 12,000 hits. A search for patient experience and heart failure without quotation marks with articles from the last five years gives me 61,000 hits. Which hit list do you prefer? And which hit list do you think gives you the most useful hits?

Search with AND or OR

By combining search terms with the Boolean operators AND, OR, NOT, you can limit or expand your search. Most databases automatically add AND between two search terms. The Boolean operators are usually written in English and in uppercase letters.

AND

Use AND when all search terms must be included in the document. This limits the search and gives fewer hits. E.g. car AND fuel.

OR

Use OR when the search term has synonyms or different spellings. E.g. car OR vehicle. Expands the search and gives more hits.

NOT

Use NOT to exclude search terms that may not appear in the document. e.g. fuel NOT aviation. NOT should be used with caution so you don’t exclude relevant documents. Limits the search and returns fewer hits.