Grey Literature is research information that is public (not behind paywalls).
It can include government reports, web content, documents from professional organizations, and conference abstracts. It might be relevant for your literature review.
This occurs when you don't do a thorough search of the existing literature. Your review doesn't need to find every document ever published, but should not be misleading. It will be misleading if you leave out whole categories of studies or only look at a haphazard section of studies.
Ways to avoid selection bias:
AI-assisted literature searching applies artificial intelligence and machine learning to the act of searching the literature, possibly finding connections that you wouldn't normally find. The tools below are a starting point.
Raxter
— https://raxter.io
Research Rabbit
— researchrabbit.
Iris
— https://iris.ai
Scite (paid app | instructions)
— https://scite.ai
Before you can searching for the existing literature, you need to make sure you know what is meant by "the literature," which is usually defined as a collection of all the scholarly writings on a topic. The literature can include peer reviewed articles, books/ebooks, conference proceedings, theses/dissertations, documents published by governmental agencies and non-profit organizations, and other forms of gray literature.
The best place to search for sources is in scholarly databases. The Library provides online access to these for free to current U-M students, faculty and staff. On the Library's homepage, there's a list of commonly used databases underneath the search box (shown below). The Library has access to hundreds of databases. Not sure which ones to use? Contact a Subject Specialist.
Library Subject Specialists are available to help throughout the literature review process, including recommending which scholarly databases to search based on your topic. On the Library's homepage, click Research and Scholarship (on the top toolbar), then click Help with Research and finally click Find a Specialist.
Why? Google doesn't divulge how they determine if a document is scholarly or not (whereas scholarly databases do). Sometimes GoogleScholar includes documents that aren't scholarly, like this school lunch menu.
Before using a document that you find in Google Scholar, you'll need to determine if it is from a credible source by researching the author, publication venue, etc.
A search strategy translates your research question into search terms. See an example below.
Research question | Concepts | Search terms |
What are the ethical considerations when using artificial intelligence to document climate change? |
1. ethics 2. artificial intelligence 3. climate change |
1. ethic* 2. "artificial intelligence" OR AI OR "machine learning" 3. "climate change" |
Look over the searching techniques on the Searching Tips tab to learn how to combine your search terms.
The screenshots below shows how you can enter your search terms into two different databases, Scopus (top) and ProQuest (bottom). Searches can be built using multiple search boxes (as shown below).
You can also build your search using a single search box (as shown below).
Remember: a comprehensive literature review (like for a dissertation) will require more sources than a selective literature review (like for a course assignment).
Searching for, reading and understanding the existing literature is more of an art than a science. The more you do, the more you'll understand the current state of research and therefore know if you've found enough literature.
New literature is being published daily. You must stop searching at some point.
Consider the volume of research on your topic. A larger volume equates to more searching. For example:
Type II diabetes = large amount of literature
Multiple Myeloma [rare cancer] = smaller amount of literature
Evaluate the resources available to you
Time: How much time do you have to complete this review?
Collaborators: Do you have collaborators or colleagues helping to complete the review?
Reflect on your Research Question
Continually revisit your Research Question and objectives — ensure the literature you've collected directly address your research goals.