George Boole, an English mathematician in the 19th century, developed "Boolean Logic" in order to combine certain concepts and exclude certain concepts when searching databases.
(Image from The Popular Science Monthly, Volume 17 .)
PICO stands for Population, Intervention, Comparison and Outcome.
PICO is used to create a researchable question based on a clinical situation you have encountered. Based on your PICO question, you will identify keywords and/or subject terms to use in database searches. When starting your search, you will want to focus your keywords and subject terms on your P and I. For example:
Research Question: Does caffeine intake in children cause stunted growth?
I: caffeine intake
C: children with no caffeine intake
O: stunted growth
When starting the search, you would want to focus your search terms on children and caffeine.
A generic search string for this search may look like this:
(child* OR adolescen* OR teen* OR toddler* OR baby OR babies OR infan* OR youth*) AND (caffein* OR coffee* OR soda* OR tea*)
Boolean logic is a building block of many computer applications and is an important concept in database searching. Using the correct Boolean operator can make all the difference in a successful search.
There are three basic Boolean search commands: AND, OR and NOT.
AND searches find all of the search terms. For example, searching on dengue AND malaria AND zika returns only results that contain all three search terms. Very limited results.
If you're searching for a phrase rather than just a single word, you can group the words together with quotation marks. Searching on "dengue fever" will return only items with that exact phrase.
It's a lot like basic math. (2 × 4) + 1 = 9 but 2 × (4 + 1) = 10
Think of your search in concepts, then put those concepts inside parentheses. Different databases have different rules about combining searches. To make sure you get the search you want, use parentheses - every database follows those rules. For example:
dengue OR malaria AND zika can be interpreted as
Controlled vocabularies are searchable thesauri or collections of terms that are used to index, catalog, and search databases. Using a database's controlled vocabulary often helps provide better results, which is why it is important that complex search strategies use a combination of controlled vocabulary terms and keywords. Controlled vocabularies that you may run into while conducting systematic reviews may include MeSH, CINAHL Subject Headings, and the APA Thesaurus of Psychological Index Terms.
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