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Finding scientific information

Boolean operators OR, AND & NOT

When you search with more than one search word, you need to tell the search engine what the relationship between the words is. For that we use Boolean operators:

  • OR operator with alternative words
  • AND operator with compulsory words
  • NOT operator to exclude a word.

The order of operations is usually AND before OR. You can override the order by using paranthesis ().

Databases have search boxes where you type in the search words and operators.

Some databases (e.g. Oula-Finna) require that the Boolean operators be capitalized, but with most other databases it does not matter.

OR operator

OR operation searches for references that have one or more of the search words. The order of the words does not matter.

 

OR operator allows you to search for the same topic with a variety of words, therefore broadening your search.

  • words with a similar meaning, synonyms
    • adolescen* OR teen* OR pubert* OR young* OR youth OR juvinile
  • same word in a different language
    • human OR ihminen OR "homo sapiens"
  • broader or narrower terms, related terms
    • famil* OR parent* OR mother* OR father* OR sibling*
    • "circular economy" OR recycl* OR sustainab*
    • "social media" OR facebook OR tiktok OR instagram
  • different spelling
    • organisation* OR organization*
    • radiotherap* OR radio-therap* OR "radio therap*"
  • search word in the end of a compound noun
    • bully OR cyberbully
    • game OR videogame
  • same words in different order, e.g. names
    • "Marie Curie" OR "Curie Marie"
  • abbreviations and the complete phrase
    • iot OR "internet of things"
  • opposite meanings
    • inclusi* OR exclusi*
    • "physical activity" OR sedentary
  • when truncation would give too many irrelevant results
    • sing* > sing, singing, single, singularity, Singapore etc.

sing OR singer OR singing OR song

AND operator

AND operation searches for references that have all of the search words. The order of the words does not matter.

  • "marine life" AND pollution AND depopulation

Quite often AND operation is the default operation in databases. In that case it can be left unwritten.

  • pisa (finland OR finnish OR sweden OR swedish)
  • "artificial intelligence" radiology

 

AND operator narrows down the search

  • combines different topics
    • (kindergarten* OR "early childhood education") AND (multicultur* OR immigra*)
  • adds context (e.g. location, age group) to a topic
    • pisa AND (finland OR finnish)
    • (adolescen* OR teen* OR pubert* OR young* OR youth OR juvenile) AND (diet* OR food OR beverage OR eating OR nutriti* OR appetite OR malnutriti* OR drinking)
  • adds a definition
    • online AND education
  • adds a comparison
    • pisa AND (finland OR finnish) AND (sweden OR swedish)

NOT operator

NOT operator excludes a specific search word from the search results.

  • (pandemic OR epidemic) NOT covid-19
  • invest* NOT investigat*

For example, by searching ((pandemic OR epidemic) NOT covid-19) you will get all references that mention pandemic or epidemic, but all the ones mentioning covid-19 will be excluded.

Be careful when using NOT operator. You might lose relevant references. The search engine does not understand why certain word is mentioned in the record. If it finds the excluded word, it will eliminate it from the search results, no matter how well the reference fits your other search words.

Boolean operators