Evidence-Based Practice Toolkit for Nursing

Created by OHSU Clinical Inquiry Council


When appraising research, keep the following three criteria in mind:

Trials that are randomised and double blind, to avoid selection and observer bias, and where we know what happened to most of the subjects in the trial.

Trials that mimic clinical practice, or could be used in clinical practice, and with outcomes that make sense. For instance, in chronic disorders we want long-term, not short-term trials. We are [also] ... interested in outcomes that are large, useful, and statistically very significant (p < 0.01, a 1 in 100 chance of being wrong).

Trials (or collections of trials) that have large numbers of patients, to avoid being wrong because of the random play of chance. For instance, to be sure that a number needed to treat (NNT) of 2.5 is really between 2 and 3, we need results from about 500 patients. If that NNT is above 5, we need data from thousands of patients.

These are the criteria on which we should judge evidence. For it to be strong evidence, it has to fulfill the requirements of all three criteria.

Source:  Critical Appraisal. Bandolier.

How To Read a Paper

Dr. Trisha Greenhalgh's clearly written papers (full-text links to each below) discuss how to critically appraise the medical literature. These articles appeared originally in the British Journal of Medicine and were later produced as a book:  How to Read a Paper.

Evidence Appraisal

The Johns Hopkins Nursing EBP Evidence Level and Quality Guide is provided via the link above. 

There are lots of other evidence appraisal resources and tools available in the eBook, Johns Hopkins nursing evidence-based practice : Models & Guidelines

(From off-campus log in with your OHSU network username and password)

Dang, D., & Dearholt, S.L. (2018). Johns Hopkins nursing evidence-based practice : Model & guidelines (3rd ed). Sigma Theta Tau International.

How To Read a Paper eBook

How to Read a Paper: The Basics of Evidence-based Medicine is available as an eBook from OHSU Library.  Read it online: