Once you run searches in the databases using your PICO keywords and retrieve articles, you will need to appraise them for quality.
Depending on the type of study (the research design), a source will be considered a higher or lower level of evidence. This is also called the hierarchy of evidence or evidence pyramid.
Because of their rigorous design, systematic reviews and randomized control trials are considered high levels of evidence. Expert opinions and textbooks are considered low levels of evidence. When you search the literature, you can expect that as the quality increases, the number of studies will decrease.
Watch the brief video and read the article below to learn more about the levels of evidence that you will encounter in your searches of the nursing literature.
Levels of evidence
Before any evidence is applied to your practice, you must first assess each article for relevance, possible bias, and validity. Check out the resources below to learn more about appraising evidence.