Observational epidemiologic studies are a type of nonexperimental research in which exposure is not controlled by the investigator. Observational studies are by far the most common form of clinical research because of their relatively low complexity, cost, and ethical constraints compared to randomized trials or other forms of clinical experimentation. Bias, confounding, and issues with validity are more common in observational studies. Observational studies can be retrospective or, in some cases, prospective. Common forms of observational studies in clinical research include cross-sectional studies, ecologic studies, case-control studies, and cohort studies.
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Rothman K. Modern epidemiology, vol. 93. 3rd ed. Philadelphia: LWW; 2008. p. 100.Google Scholar
Woodward M. Epidemiology study design and data analysis. 3rd ed. Boca Raton: CRC Press; 2013. p. 19.Google Scholar
Häuser W, Schmutzer G, Hilbert A, Brähler E, Henningsen P. Prevalence of chronic disabling noncancer pain and associated demographic and medical variables: a cross-sectional survey in the general German population. Clin J Pain. 2015;31(10):886–92.CrossRefGoogle Scholar
Shah A, Hayes C, Martin B. Factors influencing long-term opioid use among opioid naïve patients: an examination of initial prescription characteristics and pain etiologies. J Pain. 2017;18(11):1374–83.CrossRefGoogle Scholar