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Cross-Sectional Study

Olly Tree Applications presents USMLE Biostatistics... a unique, yet easy to use study tool for the USMLE. It is completely free and comes with absolutely no advertisements. Currently only on Android. https://play.google.com/store/apps/de... Cross-sectional studies analyze information from a SPECIFIC MOMENT/PERIOD. It is an observational type of study, because researchers do NOT interfere with their subjects or intervene in any way. Characteristically, exposures and outcomes are be measured simultaneously. Consequently, it can be difficult determine which came first, the exposure or the disease. DESCRIPTIVE cross-sectional studies assess the PREVALENCE of a condition (but NOT the incidence) and its distribution within a population. The prevalence of a condition can be simply calculated by dividing the number of people with a condition, by the total number of people in the population. ANALYTICAL cross-sectional studies evaluate the association of disease with other characteristics of the population. However, an association between exposure and outcome does NOT imply a cause-effect relationship. The degree of association, particularly when the study involves a chronic disease, is usually measured with the prevalence odds ratio. A complicating factor in cross-sectional studies is the susceptibility to a variety of types of BIAS (e.g., unacceptability bias, recall bias, and etc.).