Search Methods for Finding Academic Literature

Watch the video below to learn more about controlled vocabulary, Boolean operators, filters, and snowballing, or check out the information further down the page to read about it.

Reach out to library staff for video passwords.


Controlled Vocabulary
Databases use a specific language; just like in real-life, if you don't know the language, it can be difficult to find what you are looking for. If you are using normal human conversational language to find research, but the articles in a database are organized using medical terminology, anything you do find will be only a fraction of the story.

You can use the database’s thesaurus to find subject terms. Different databases may use different subject headings, so it is a good idea to check what terms the database actually uses. MEDLINE uses MeSH (Medical Subject Headings), which is what the OCOM Library also uses to organize materials. 

Filters / Limits
Filters allow you to limit the results you get in a database. You might think having a lot of results come up in your search is great, but having too many results can be overwhelming. What would you do if your search came up with over 2,000 hits? Would you have the time, patience, and attention span to scan each article to see if it is worth your time? Your answer is probably no. And that is fine -- because that is why filters were created. Filters allow you to narrow down your search results to just those articles that are relevant to your search. There are many kinds of limits -- you can limit by type of research (RCT, systematic review, case study, etc.), by year published, by subject heading -- some databases even let you limit by the subject species (such as tests involving rats) or by gender or age (only studies done on adolescent females).

CLICK HERE to see the boolean search terms for finding specific types of research (i.e., Systematic Review, Randomized Controlled Trial) in PubMed.

A word to the wise: Even filters have their limits. When you search multiple databases at once in EBSCO, each of those databases has their own set of individualized filters. The problem with searching in multiple databases that use different filters is that if you turn on a filter, you may be limiting perfectly good results from databases that don't use those filters.

To conduct a completely comprehensive literature review, you should search each database independently, which will allow you to take full advantage of the limits set up for that database.
Boolean Operators

Boolean operators are how we modify searches. For example, let's say you are searching for acupuncture or herbal treatments for amenorrhea.
Use Boolean operators (AND, OR, NOT) to combine or exclude search terms:
AND: Narrows search results
OR: Widens search results
and NOT: Narrows search results by excluding unwanted terms
Quotes: Search an exact phrase

If you wanted to find information about acupuncture OR herbs in the treatment of amenorrhea, you would use parenthesis to set your search phrase. Look at this search phrase:
Amenorrhea AND Acupuncture OR Herbs

Boolean formulas read like a mathmatical formulas, from left to right. So this search phrase would retrieve Amenorrhea AND Acupuncture. OR it would just search Herbs. In order to remedy this, you should use parenthesis to define your search parameters:
Amenorrhea AND (Acupuncture OR Herbs)

You can use the asterisk symbol to create truncation and wildcards, which will allow you to account for variations in spelling. 
Wom*n = woman or women
Acupunctur* = acupuncture or acupuncturist

Find the Help section in the catalog / database you are searching to learn more.
Snowballing is when you find a resource and scour the bibliography for related references. This will lead you to other resources, which in turn may lead you to even more references. This is a great way to find citations that might not be indexed in large databases or grey literature (see the next section for more information on grey literature). Sometimes all it takes is one really good journal article to get you snowballing. You might hear other terms for this as well, such as "hand searching," but snowballing is my favorite because it is such a great metaphor for this activity.

When you find references in a bibliography, you are looking at older research -- stuff that was written that influenced the newer article or book. But using a Google Scholar function, you can flip this and search for newer research. If you've found a good article, you can try searching for it in Google Scholar. When you find the article, there will be a link that says, "Cited by ___," with the number of found citations. If you click on the link, you will see all the newer citations that have referenced this article.

Unpublished Studies / Grey Literature
Grey literature is literature that is not published by conventional means. Some examples of grey literature include conference proceedings, government documents, wikis and blogs, theses, and clinical trial registeries.

Researchers and publishers often do not publish results from studies that show negative or null  results. This is not just a problem of publishers refusing to publish reports, but is often a self-imposed censorship by researchers who do not wish to showcase their unsuccessful trials. The problem with this is that journal publications are how researchers communicate findings to one another. You won't know that a type of therapy is not successful if people don't publish those results.

Grey literature is important because it fills this evidence gap. By searching for information that is not published, you can find information that you wouldn't necessarily find in commercial publications due to publication bias.
You can read more about searching for Grey Literature by checking out UBC's Guide.

Types of Clinical Questions
There are two main types of clinical questions: Background questions and Foreground questions.
Background questions are generally posed towards the basic understanding of a topic. These types of questions generally have only 2 parts: A question root (who, what, when, where, how, why) and a disorder, test, treatment, or other aspect of health care. Often these questions can best be answered by using a textbook or consulting a clinical database. Some sample background questions:
  • What patient populations are most likely to be affected by colon cancer?
  • What are the symptoms of bacteremia?
  • What are some common treatments for low back pain?

Background questions can be answered by using secondary resources such as informational articles, reference books, or clinical databases, and authoritative answers can be found in a short amount of time.
Foreground questions, on the other hand, are much more complex. They often include a broad range of topics including biological, psychological and sociological issues. Some examples of foreground questions include:
  • What are the causes of surgical wound infection following hip replacement?
  • What factors influence parents' decisions regarding the refusal to immunize their children?
  • Does the use of cell phones increase the incidence of brain cancer?

Due to the complexity of the question, foreground questions generally require the use of scientific studies to answer, and may take much more research and time to answer.
Creating a Clinical Question (PICO)
PICO is an acronym that can help you create a well-built clinical question by identifying the key aspects of a complex patient presentation:
     P=Patient or Population and Problem;
     I=Intervention or Indicator;
     C=Comparison or Control (optional);

In older adults (P) does Tai Chi (I) compared to other forms of exercise (C) reduce fall risk (O)?

There are a couple of other letters you can also add to this mnemonic to ask different types of questions (i.e., PICOTT)
Timeframe: Time it takes to demonstrate a clinical outcome or how long patients are observed.
Type of Study: What kind of study would best answer this question (i.e., RCT, Case Series, etc.)

Does telemonitoring blood pressure (I) in African-Americans with hypertension (P) improve blood pressure control (O) within 6 months of initiation of the medication (T)?
Watch this video to learn how to use the PICO method to create a searchable clinical question. Then use this worksheet to create your own searchable question!
Turning PICO into a Literature Search
PICO is a search strategy formula. The components of PICO help pinpoint keywords that you will be able to directly input into a database to find research. If you are unable to find articles that utilize that intervention, try using alternate terms. If that still does not work, this may mean you have stumbled upon a gap in the evidence -- it is possible that research has not been done or published on this particular topic. If you are having trouble finding literature on your topic, you can always ask a library for help.

So let’s look back at our earlier example of Tai Chi helping to reduce risk of falling.
P=The patient is older adults. Keywords could include elderly, geriatric, aging. The MESH subject heading for this is aged, but databases like PubMed also allow you to utilize filters for patient information. So you can try out some of these keywords, but you could also try leaving out this keyword and adding a filter.
I=The Intervention is Tai Chi. Tai Chi is spelled a number of ways -- Tai chi chüan, Tàijí quán. So you may want to include alternate spellings  (“Tai chi” OR Taiji OR “Tai ji”)
C=The Comparison intervention is other forms of exercise. This is pretty vague, using the term “usual care” can also be useful. You could try both terms by using  (exercise OR usual care).
O=Finally, the Outcome is reducing fall risk. The generic MESH term that covers risk of fall is Accidental Falls, but there is also a sub-term that is prevention & control*. So you could use Accidental Falls/prevention & control*

Your boolean search could look something like this:

(elderly OR  geriatric OR aging OR aged) AND (“Tai chi” OR Taiji OR “Tai ji”) AND  (exercise OR usual care) AND (Accidental Falls/prevention & control*)

PICO is focused around an intervention. If you are not including an intervention in your literature search, you may spend a lot of time combing through results just to discover what kinds of interventions are available, and then having to narrow down your results. This can be avoided and time can be saved by doing some background research first, understanding what types of interventions are available, and incorporating that into your search.

Push notifications are a way of getting alerted about new research. Say you are interested in keeping up to date about acupuncture / IVF research; rather than having to replicate your search each month or couple of months to see what is new, you can set up alerts that will automatically notify you when new material is published that meet your criteria. If you've ever used RSS feeds, you are already familiar with this concept: instead of visiting every website that you like, you can subscribe to the RSS feeds of your favorite sites, which will be aggregated into one place (your RSS reader) for your viewing pleasure. Here are a couple of ways you can use push notifications to stay up-to-date one newly published medical research.

PubMed / My NCBI
  1. Click on the Sign In button in PubMed.

  2. Register for an NCBI account, or log in using your Google account
  3. Once you are registered and signed in to My NCBI, you see your dashboard. Here, you can search for articles in PubMed, create a bibliography or a collection, see recent searches, create active filters, and manage your saved searches.

  4. In order to save a search, simply do a keyword search in PubMed, then click on the "Create alert" link.

  5. Once your search has been saved, you can set it up so new articles that match your search will automatically be emailed to you. You can always edit your search and modify your keywords or filters if you are receiving too many or too few results.

  6. Sit back and wait for your articles to be delivered to your inbox!
Journal Alerts

You can also get notifications from specific journal publications about newly published articles that meet your search criteria. Most journals allow you to sign up for notifications by visiting the journal page on the publisher's site.

De Gruyter's site has a very clear "Get New Article Alerts" link:

Liebert has an online portal for registered users to manage their notification settings, and even get free access to select articles in their field:

RSS Feeds
If you see this icon , it mean that an RSS feed has been detected. In a nutshell, RSS feeds allows you to aggregate content from web resources (such as blogs, news sites, or in this case, an online journal) so you don't have to visit every site that you are interested in keeping up with. For example, you could follow the RSS feeds from a couple of acupuncture blogs you like, get updates from Pubmed about all the new articles that have to do with acupuncture and pregnancy, and be sent the table of contents for each new issue of Fertility and Sterility. By using an RSS reader (such as Pocket, Feedly, or Instapaper), you can view all of this information in one place -- you don't have to just periodically check each of these different websites for updates. Instead, the updates come directly to you.
Google Alerts
If you are interested in more general interest stories or medical topics in the popular press, you can also get Google to send you alerts when new pages with your search terms hit the internet. Login to your OCOM email account (or your personal gmail account) and go to: Enter your search terms and your email preferences and voila! You will magically get an email when there’s something new on the topic on the internet. (And you can totally use it for vanity searching, we won’t tell!)