Is secondary research summarising the primary evidence.National Institute for Health and Care Excellence (NICE). This method is also used to reduce bias.' Outcomes are measured at specific times and any difference in response between the groups is assessed statistically. The groups are followed up to see how effective the experimental treatment was. One group (the experimental group) receives the treatment being tested, the other (the comparison or control group) receives an alternative treatment, a dummy treatment (placebo) or no treatment at all. 'similar people are randomly assigned to 2 (or more) groups to test a specific drug or treatment.The study uses explicit and reproducible methodology.The authors of the article also conducted the study or trial.The results are published as a journal article.

Is a single, primary study using a specific study design.A hierarchy of evidence for assessing qualitative health research. The Centre for Evidence Based medicine at Oxford also has a handy study design tree.ġ. Daly J, Willis K, Small R, Green J, Welch N, Kealy M, et al. Levels of evidence from essentialevidenceplus.The pyramid is only one example of levels of evidence. There is also a pyramid for qualitative research 1. Although not a study type in the true sense clinical practice guidelines are often a 'go to' resource in EBP. For example it may not be ethically appropriate to do an rct, or some studies use case-control or cross-sectional methods. If there are no recent systematic reviews or meta-analyses and your topic relates to treatment or therapy, look for a randomised controlled trial, or the next best and appropriate primary study. There are also umbrella reviews also known as reviews of systematic reviews. These are higher tier evidence sources (sometimes referred to as secondary studies ie studies that combine and appraise collections of usually single or primary research on a particular topic or question). In most cases this means you are ideally looking for a type of study known as a systematic review (or even better a systematic review with a meta-analysis for a quantitative review, a meta-synthesis for a qualitative one). You don't want just any type of article and any type of research methodology for EBP. Before you start searching you need to know not all research is the same.

Types of studies