Unlike cohort studies, which follow groups over time, Case Control Studies take medical histories of patients and seek to draw statistical conclusions based on similarities in the medical histories of the patients with the condition that are not existent in the medical histories of the patients without the same condition. However, they tend to be very long studies, sometimes generational, and, because they are not randomized, are less reliable than a randomized controlled trial.Ĭase Control Studies look at a group of individuals with a specific condition and compare them to a group of people without the same condition. They are a very good method to track long-term health effects that it may be unethical to test as a randomized controlled trial, for instance exposure to a specific pollutant (smoking, radiation, etc). This allows the study to test a specific therapy against either no-therapy or a different course of treatment.Ĭohort Studies are observational studies that compare a cohort already undergoing a treatment or with a specific, unique exposure to a separate cohort that is not utilizing the same treatment or exposure over a period of time. They are designed with two cohort groups, a test group and a control group, ideally with patients assigned randomly to each group. Randomized Controlled Trials answer questions about the efficacy of different types of therapies. Meta-Analysis takes this process one-step further, reviewing clinical questions for which multiple Systematic Reviews exist to take into account all of their data and develop the highest level of statistical analysis. They assess the methodology, sample size, and quality of the studies, using the highest quality data available to answer specific clinical questions and develop practice recommendations.

Systematic Reviews summarize the results of a systematic literature search on a specific clinical question to develop clinical recommendations. Meta-Analysis and Systematic Reviews are the gold-standard of clinical information.

Types of studies