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CAUTION
When you use AND in a search engine, all of the terms are treated equally. You do not need to put your terms in order of importance.
PRACTICE
Topics (e.g. Allergies AND Sleep) -- question: what they have in common or how they influence each other.
Do a search for:
Next, do a search combining both topics (e.g. Allergies AND Sleep).
What do you notice?: Does the number of results increase or decrease? Are the results more relevant to your question?
Search Operator AND narrows your search by helping you find articles that discuss two different concepts.
Many databases, including CINAHL and PubMed, will automatically insert AND between your search terms. Use the following part of the guide to see how this affects your search.
If you were to look at two topics (A or B) separately, you will find plenty about each article individually. Although that is helpful for general ideas, it is better to look at the shared ground between two different topics.
Thinking about AND can get you to think about how A impacts B, what A has in common with B, and how A and B differ.
Let's say we want to know which diseases are carried or caused by insects. Start by listing insects and diseases separately.
Combine the two to see what Insects AND Diseases have in common.
Searching for Insects AND Diseases pulls "Malaria", "Cholera", and "HIV/AIDS" because those are diseases that can be carried by Mosquitos."Sting allergy" is pulled because it can be caused by Wasps or Bees. "Lyme Disease" is pulled because it is carried by Ticks.
Insects that don't carry diseases like Butterflies and Crickets and diseases not caused or carried by insects like Depression and Arthritis are excluded from the results.
Search Operator OR widens your search by helping you find articles that discuss the same concepts using different words.
OR is used in two ways.
1. OR is used if there is more than one word or phrase for your topic.
Itching OR Pruritis
Sometimes an article will use decide to use one term instead of another even if they both mean the same thing. If you only search for “itching” you will exclude any articles that say “rash” instead.
2. OR lets you look at related topics at the same time.
Itching OR Pruritis OR Rash OR Hives OR Urticaria
Just because you itch doesn’t mean you have a skin disease, but some discussions that revolve around skin diseases can still apply to itching.
Using OR
Let's say you want to look at Insects and Diseases overall. Start by listing Insects and Diseases separately.
Combine the two to see what counts as Insects OR Diseases.
Searching for Insects OR Diseases pulls everything involving Insects OR Diseases. That includes what they don't have in common like Depression because it is not a disease carried by insects and Butterflies because they do not carry diseases.
Using OR to search for alternative terms would be searching for "Insects OR Bugs" or "Diseases OR Illnesses".
When using OR for replacement terms, be sure to use parentheses to partition off the terms used. For example, if you want to search for diseases or illnesses caused by insects, use "insects AND (diseases OR illnesses)" not "insects AND diseases OR illnesses." The latter search will include all the results for "insects and diseases" and "illnesses," even those illnesses unrelated to insects.
Search for a topic (e.g. Cats or Itching) without using OR. Note how many results you get. Search for a topic that can be said in two different ways (e.g. Cats OR Felines or Itching OR Rash). Does the number of results increase or decrease?
PRACTICE
Form a question based on two common topics. Search for one topic (e.g. Cats or Itching) without using OR. Note how many results you get and how relevant they are to your question. Search for both topics (e.g. Cats OR Dogs or Itching OR Skin Disease). Does the number of results increase or decrease? Are the results more relevant or less relevant?