Observational study

Observational study

An observational study is a type of research in which individuals are observed or certain outcomes are measured. No attempt is made to affect the outcome (for example, no treatment is given). In an observational study, the researchers observe the subjects and measure their outcomes. The researchers do not manipulate variables or administer any treatments.

Types of observational studies

There are several types of observational studies, including:

• Cohort study: This is a longitudinal observational study which involves two groups of individuals — one group with a certain exposure or condition, and another group without the exposure. The two groups are followed over time to see the incidence of a certain outcome.

• Case-control study: This is a retrospective observational study. Individuals with a certain outcome are identified and compared to individuals without the outcome. The proportion of each group that was exposed to a certain factor is then compared.

• Cross-sectional study: This is an observational study that analyzes data from a population at a specific point in time. It’s often used to assess the prevalence of acute or chronic conditions, or to answer questions about the causes of disease or the results of medical treatment.

• Ecological study: This is an observational study in which at least one variable is measured at the group level. An ecological study is especially appropriate when exposure data are unavailable for individuals, when group-level variables are of interest, and when a large number of observations are needed.

Advantages and disadvantages

Observational studies have both advantages and disadvantages compared to randomized controlled trials (RCTs). They are typically easier and cheaper to conduct, and can be the only feasible method for studying certain issues. However, they are more susceptible to certain biases and confounding variables.

See also

• Epidemiology
• Clinical study design
• Longitudinal study
• Retrospective study
• Prospective study

References

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Observational study

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