Systematic reviews and meta-analyses are situated at the top of what is known as the “Evidence Pyramid” (see figure below). As you move up the pyramid the amount of available literature on a given topic decreases, but the relevancy and quality of that literature increases. Systematic reviews and meta-analyses are considered to be the highest quality evidence on a research topic because their study design reduces bias and produces more reliable findings. However, you may not always be able to find (or need to find) the highest level of evidence to answer your research question. In the absence of the best evidence, you then need to consider moving down the pyramid.
