Online/Distance Resources for Nursing Students

Tips for Weighing the Evidence:

• Research with a control group (no intervention) and an experimental group is more reliable than research without. 
• Research that is blinded—where the researchers don't know who is in which group—is better able to prove an effect than unblinded studies.
• Because statistical flukes can happen, meta-analyses and systematic reviews from respected groups like Cochrane and JBI, which take a structured look at the existing research about a topic, are best able to reach a conclusion on how complete or established a scientific position is.
• Responses matter. Scientific publishing is a conversation; papers cite each other to agree or disagree. Collecting articles that refer to each other gives you a better picture of your topic. 

When you start researching you will encounter many different types of evidence such as systematic reviews, randomized controlled trials, clinical guidelines and opinion articles.  These different resources will not all have the same "weight" in terms of reliability and trustworthiness.  

Evidence Level hierarchies are systems used to rank evidence according to certain criteria. There are many hierarchies, including the examples on this page.

Source: Hopp, L., & Rittenmeyer, L. (2012). Introduction to evidence-based practice: A practical guide for nursing. Philadelphia: F.A. Davis.

What's NOT in the Included in the Levels of Evidence?

There are some types of sources you may encounter that aren't included in the Levels of Evidence.

Informational (non-experimental) sources may be useful for your understanding but should not be cited as scientific evidence.

Examples include: Informative articles, trade journal, magazine, and news articles, blogs, and popular sites such as Wikipedia.

• These types of sources do not reflect primary research, nor are they an expert review of primary research the way clinical practice guidelines or systematic reviews are.
• They may refer to or summarize research articles. Locate the research article rather than cite an author's summary of it. Some informational sources will include links to or citations for the original sources. 

Content adapted with permission from Grand Canyon University Library: https://libguides.gcu.edu/EvaluatingSources