When appraising research, keep the following three criteria in mind:
Quality
Trials that are randomized and double blind, to avoid selection and observer bias, and where we know what happened to most of the subjects in the trial.
Validity
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).
Size
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.
Dombrowsky T. (2023). Linear regression: A beginner's guide for nursing research. Nursing, 53(9), 56–60. https://pubmed.ncbi.nlm.nih.gov/37616410/
Some points to consider when evaluating information on the Internet or in print.
If a claim conflicts with...
Avoid confirmation bias:
Source: Vaughn, L. (2019). The power of critical thinking (6th ed., Chapter 4). Oxford University Press.
Educational Resources:
Understanding Health Risks (NIH News in Health)
Christine Laine, Dianne Babski, Vivienne C. Bachelet, et al. Predatory Journals: What Can We Do to Protect Their Prey?. Ann Intern Med.2025;178:294-296. [Epub 7 January 2025]. doi:10.7326/ANNALS-24-03636
Avoid making big decisions based on one study as there is always some uncertainty in science.
Worsham, C. and Jena, A., 2021. Evidence-Based Medicine Shouldn’t Mean Treating Everyone the Same. [online] Harvard Business Review. Available at: <https://hbr.org/2019/01/the-art-of-evidence-based-medicine> Accessed 29 September 2021
Nursing and allied health literature; defaults to peer-reviewed articles. Limiters include qualitative and quantitative research, evidence-based practice, randomized controlled trial studies, and more.
Healthcare information covering nursing, allied health, complementary medicine, and more. Defaults to peer-reviewed articles. Includes additional databases. Limiters include interviews, evidence-based healthcare, dissertations and theses, and literature reviews.
A Systematic Review vs. Meta-Analysis vs. Literature Review vs. Scoping Review. Scribbr, 2022.
