Literature Reviews

In this section we will review the steps you take in order to perform an effective search using databases and other resources. Every search begins with a research question or topic. If you have not developed your research question or chosen your topic you will need to complete this first step.

Step 1: Develop a research question or choose a topic

Step 2: Brainstorm your search terms, including MeSH terms, that should be included in your search

Step 3: Use Boolean logic to combine your terms

Step 4: Perform a preliminary search to determine if their is any literature on your topic (You can schedule an appointment with a librarian to assist you with performing your preliminary search.)

Step 5: Keep a record of your search strategy

Develop your question

Begin the process by identifying what you have an interest in investigating. What do you what to know? What do you want to learn? Who do you want help? What medication, treatment, procedure, or therapy do you want to research? Is there a specific population you want to focus your research on? Keep in mind that the more narrow your topic or focused the research question, the less you will find published in a database or online. It is recommended that you begin with a broad search to determine what has been published on a specific patient population, medication, procedure, therapy, etc.

PICO can be a helpful way to construct your search. PICO stands for: 

• Patient
• Intervention
• Comparison
• 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. 

You can use PICO to develop your research question.

• Patient or population/disease: Which population are you studying? (Consider age, gender, ethnicity, group with a certain disorder, etc.)
• Intervention, prognostic factor, or exposure: What do you want to do for the patient? (Consider therapy, exposure to a disease, risk behavior, prognostic factor, preventative measure, or diagnostic test)
• Comparison or control: Are you comparing two interventions or variables? (Consider absence of disease, absence of risk factor, or use of placebo)
• Outcome: What is the expected result or what do you hope to accomplish, improve, or affect? (Consider disease incidence, accuracy of a diagnosis, rate of occurrence of adverse outcome, survival or mortality rates.) 

Brainstorm for terms, including MeSH terms

Unlike Google, PubMed and other abstract databases are not capable of automatic term mapping. Automatic term mapping refers to a database's ability to automatically look for synonyms or similar search terms to the those entered by the user. In Google, you can search on "used cars for sale" and you'll get results that include "used SUVs for sale" or "used convertibles for sale" or "used Jeeps for sale." PubMed (and other abstract databases) will search on exactly—and ONLY—the word or exact phrase you give it. Though PubMed is starting to implement automatic term mapping, the best way to ensure as thorough a search as possible is to search on all possible terms.

Example: 

• Searching on "pressure wounds" returns 52 articles.
• Searching on ("pressure wounds" OR "pressure injuries" OR "pressure sores" OR bedsores) returns over 20,000 articles.

MeSH terms, PubMed's controlled vocabulary, are another way to enhance your search. Our MeSH Guide has more information.

Boolean Operators (Using AND, OR NOT)

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.

AND, OR, NOT

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. AND limits the number of results.
• OR searches find either one term or the other. Searching on (dengue OR malaria OR zika) returns all items that contain any of the three search terms. OR expands the number of results.
• NOT eliminates items that contain the specified term. Searching on (malaria NOT zika) returns items that are about malaria, but will specifically NOT return items that contain the word zika. This is a way to fine-tune results. (Note: sometimes AND NOT is used; serves the same function as NOT.)

Using Boolean Search with Exact Phrases

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.  

When to use parentheses?

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 more information on using Boolean logic, check out our Boolean Logic Guide

Perform a preliminary search

This will help you determine what has been published on your topic or research question. The preliminary search is the point in the research process where you can identify a gap in the literature.

Use the search strategies above to help you get started.

If you have any questions or need help with developing your search strategy, please schedule an appointment with a librarian. We are available to meet online and in-person.

Keep a record of your search terms

You will probably need to go back and re-do this search with slight alterations. It is easier to start with your old search than starting all over again.