Image from the Duke University EBP guide 

The patient is at the center of evidence-based medicine decision-making. 

1. Assess the patient with a thorough clinical evaluation to gather all the pertinent data about the patient(s) or population(s)
2. Ask  patient-oriented, relevant, answerable questions about the health status and context of patients or populations 
3. Acquire the best available evidence to answer the question 
4. Appraise the evidence critically for validity and applicability to the problem at hand
5. Apply the evidence by engaging in collaborative health decision-making with the patient(s) or population(s) 

Evidence cycle description from the Duke Program on Teaching Evidence-Based Practice 

You can learn more and access resources relating to EBM from the Evidence Based Medicine Research Guide.

Meta Analysis – a type of systematic review that combines the results using accepted statistical methodology as if they were from one large study. 

Systematic Review – an exhaustive, unbiased, and reproducible review of the literature that synthesizes findings from studies meeting pre-specified eligibility criteria, with the goal of answering a narrow research question (typically in PICO format). For additional information on systematic reviews, see the systematic review guide.

Randomized Controlled Trial (RCT) – a prospective, analytical, experimental study using primary data generated in the clinical environment. Individuals similar at the beginning of the study are randomly allocated to two or more treatment groups, and the outcomes of the groups are compared after sufficient follow-up time. A study that shows the efficacy of a diagnostic test is a prospective, blind comparison to a gold standard. This is a controlled trial that looks at individuals with varying degrees of an illness and applies diagnostic tests to each individual (the test under investigation and the "gold standard" test).

Cohort  Study – an analytical, observational study of a population (or cohort) who had, have or will have a specific exposure or treatment of interest. The outcome of this cohort is compared to the general population or another group that has not been exposed to the exposure or treatment of interest. Cohort studies are susceptible to bias because the two groups may differ in ways beyond the variable in the study. 

Case-Control Study – a retrospective, analytical, observational study often based on secondary data in which individuals with a condition or outcome are compared with individuals who do not have the same condition or outcome, but that have the same risk factor.  Often using medical records or patient recall, researches look back in time to identify possible exposures. However, due to the potential for many forms of bias in this study type, case control studies provide relatively weak empirical evidence even when properly executed. 

Case Series or Case Report – anecdotal evidence. A description of a single case (or several cases), typically describing the manifestations, clinical course, and prognosis of that case. Due to the wide range of natural biologic variability in these aspects, a single case report provides little empirical evidence to the clinician. They do describe how others diagnosed and treated the condition and what the clinical outcome was.

For additional information on study designs, see the Center for Evidence-Based Medicine's page.