The hierarchy of evidence is a system of grading and estimating the strength of evidence used in research. It constitutes a set of terms and definitions, as well as criteria broadly applied by researchers and peer reviewers when determining how reliable the presented evidence is (Doleac, 2019). There are many different systems utilized in specific areas of research, such as medicine, science, physics, biology, mathematics, and others (Doleac, 2019). Nevertheless, these systems typically have points of agreement with one another to facilitate cohesion between different disciplines.
In medicine, the most reliable forms of evidence include meta-analyses and randomized controlled trials. These sources of evidence are considered the most reliable as they deal with primary evidence and specific research questions that they seek to address (Doleac, 2019). It helps avoid ambiguity and misinterpretation of findings. These are followed by cohort studies and case-control studies, which have much less rigor when compared to the former two (Doleac, 2019). Finally, there are case reports and cross-sectional surveys, which are considered the lowest levels of evidence.
Historical research differs from medicine due to the absence of objective sources and experimental forms of research. While randomized controlled trials are still present, they are much harder to get a hold of (Doleac, 2019). In many cases, historians have to rely on comparative analysis of events with or without intervention, as well as opinions and reports of authorities in regard to the task (Doleac, 2019). They have to evaluate the rate of bias and the chances of information being misinterpreted and misrepresented.
Overall, the hierarchy of evidence is an agreement between different scientific authorities to impose uniformity of standards on research. While it differs from one research to another, these guidelines offer a general sense of formality and understanding of what is expected of specific sources without going into detail (Doleac, 2019). At the same time, it is possible for specific pieces of evidence to be more relevant to the study based on methodology and specifics of findings. Nevertheless, the hierarchy of evidence remains an important tool that is not easily disregarded.
Reference
Doleac, J. L. (2019). Evidence-based policy” should reflect a hierarchy of evidence. Journal of Policy Analysis and Management, 38(2), 517-519.