A comprehensive literature review surveys the "literature" - scholarly articles, books and other sources (e.g. dissertations, conference proceedings) - relevant to a particular issue, area of research, or theory. The literature review summarizes, interprets, and critically evaluates the significant work on the topic.

A well-done literature review will guide future research on a topic, allowing you to place your own research in the context of other works.

Too much information? Less, but more relevant, information is key. Consider:

• Theoretical approach:  Limit your topic to a particular approach to the issue.  For example, if your topic concerns cloning, examine the theories surrounding the high rate of failures in animal cloning.
• Aspect or sub-area:  Consider only one piece of the subject.  For example, if your topic is government and health care, investigate government oversight of hospitals.
• Time, Population group, or Geographical location: For example, limit your topic to the 20th century, teenagers, low-income households, urban areas, or Michigan

Not enough information? Think of related ideas, or read some background information first. Consider:

• Your topic is too specific.  Generalize what you are looking for. For example: if your topic is genetic diversity for a specific ethnic group in Ghana, Africa, broaden your topic by generalizing to all ethnic groups in Ghana or in West Africa.
• Your topic is too new for anything substantive to have been written.  If you're researching a recently breaking news event, you are likely to only find information about it in the news media. Be sure to search sources that contain articles from newspapers. If you are still not finding enough in the news media, consider changing your topic to one that has been covered more extensively.
• You have not checked enough databases for information.  Look for other databases beyond your subject area which might cover the topic from a different perspective. Also, use excellent searching techniques to ensure you are getting the most out of every database.
• You are using less common words or too much jargon to describe your topic.  Use a thesaurus to find other terms to represent your topic. When reading background information, note how your topic is expressed in these materials. When you find citations in an article database, see how the topic is expressed by experts in the field.

Remember, you will have to read extensively on an issue before you can define a feasible research topic. You may - and likely will - modify your topic many times as you discover new information.

(Adapted under a Creative Commons License from MIT Libraries)

In order to conduct an effective search, you must first identify key words, concepts, synonyms, and related terms to use in your search. 

Sample topic: how will global warming affect life in the Great Lakes states in the 21st century?

Key Words: words that convey the main ideas of your topic or question.

• global warming
• climate
• greenhouse gasses
• solar radiation

Concepts: words that describe the big ideas to which your topic is related

• ecological systems
• environment

Synonyms: words that mean the same thing as your key words

• earth temperature
• greenhouse effect

Related Terms: words that are closely related with key words, but not substitutes like synonyms

• climate change
• earth's atmosphere

(Adapted under a creative commons license from Oregon School Library Information System)

Many databases and search engines allow you to use "Boolean logic" to refine your search by connecting words and phrases together to narrow or broaden your results.

Use AND between words or phrases to narrow your results and tell the database that all search terms must be present in the resulting records.

• Searching "non-profit AND leadership" will give you results that contain both the term "non-profit" and the term "leadership"

Use OR between words or phrases to broaden your results and tell the database that either search term must be present in the resulting records.

• Searching "teenager OR adolescent" will give you results that contain either the term "teenager" or "adolescent"

Use NOT between words or phrases to indicate that the first word or phrase must be present in the resulting records, but the second word or phrase should not be present.

• Searching "higher education NOT community colleges" will give you results that contain the term "higher education" but do not contain the term "community colleges"

Truncation (or the asterisk * ) can be used to get all results that contain a term beginning with a common set of letters.

• Searching "child*" will give you results that contain the term "child," "children," "childhood," "childlike," "childish," etc.

Information can be gathered from a variety of formats:

• Journal articles (scholarly, peer-reviewed)
• Books
• Book chapters
• Newspaper articles
• Magazine articles
• Websites
• Reports or white papers
• Government documents, reports, legislation
• Social media
• Blogs
• Online forums
• Statistics
• Interviews
• Experiments

No matter the format, you must evaluate the information to determine if it is appropriate for your research need. Consider:

• Authority
  • Who wrote/created the source?  Is the author(s) affiliated with a particular institution/discipline?
• Perspective
  • Is a particular group/organization responsible for the source?  If so, what is the mission or goal of that group/organization?
  • Does the author/group have a specific perspective which might affect treatment of the topic?
• Audience
  • Who is the intended audience of the source? 
  • Is the information presented in a specific format or structure in order to appeal to a particular audience?
  • Does the nature of the intended audience impact the way in which the information is presented?
• Accuracy/Reliability
  • Are opinions presented as facts?
  • Are asserted “facts” backed up with reliable evidence?
  • Can you rely on the accuracy of the information presented?  Why or why not?
• Currency
  • How recently was the information produced?  Is it sufficiently up to date to be reliable for this topic?

Most sources you use will include references to other information, often (though not always) in the form of citations. it can be helpful to keep track of what sources relate to each other, and how.

Some databases also allow you to search for additional sources that cite a source you already have. Imagine you have found a great journal article on your topic. You can use these databases to generate a list of articles and books that cite your initial article. Web of Science, Scopus, and Google Scholar all provide tools to help you build your citation map.