Study Design and Types of Evidence
When dealing with EBP, you will often hear about the “best” evidence. This means two things:
- Not all evidence is created equal.
- Not all levels of evidence are available for every question.
Imagine you had a patient with recurring, painful acne. What kind of research would you seek to help deliver a treatment: a systematic review of several randomized controlled trials of treatments for this condition, a single case study of a patient experiencing similar symptoms, or your colleague’s third cousin, who once mentioned that “chocolate causes acne”?
These are all forms of evidence—even the last one!—but something like a systematic review, which amasses data from numerous studies to create generalizable results, will provide the broadest view of the evidence on your patient’s condition and help you devise an evidence-based treatment plan.
However, sometimes the very high levels of evidence aren’t available. As you seek higher levels of evidence, they become less common, as shown in the pyramid above. With an especially narrow topic, or one about a new phenomenon, a single case study may be the best you can find. Additionally, for some types of questions—etiology or harm, for instance—it may not be ethically possible for a randomized controlled trial to exist.
Resources:
- Cochrane Library This link opens in a new window
The Cochrane Library is a collection of databases that contain different types of high-quality, independent evidence to inform healthcare decision-making. The Cochrane Library includes the Cochrane Database of Systematic Reviews (CDSR), the Cochrane Central Register of Controlled Trials (CENTRAL), and Cochrane Clinical Answers, and a federated search feature that incorporates results from external databases.
Evaluating Resources
Adapted from Reynolds Community College Libraries
What Is A Primary Research Article?
Primary research articles
- are original scientific reports of new research findings
- do not include review articles, which summarize the research literature on a particular subject, or articles using meta-analyses, which analyze pre-published data
- usually include the following sections: Introduction, Methods, Results, Discussion, References
- are peer-reviewed (examined by expert(s) in the field before publication)
- a peer-reviewed article is not the same as a review article, which summarizes the research literature on a particular subject
Secondary sources
- are summaries or interpretations of original research – not the original research itself
- are often useful and easier-to-read summaries of research in an area
- references or citations can point the way to useful primary research articles.
- acceptable formats may include books (find these through the library catalog) and review articles (articles which organize and critically analyze the research of others on a topic)
- blogs, YouTube videos, newspaper articles, book reviews, press releases and .com websites are NOT among formats usually appropriate as sources in scientific research
