Observational Study
A study in which researchers observe participants without intervening. Includes cohort studies, case-control studies, and cross-sectional surveys.
In Depth
Much of the epidemiological evidence on cannabis and health outcomes (cancer risk, cognitive effects, mental health) comes from observational studies. These cannot establish causation due to confounding variables — cannabis users differ from non-users in many ways that independently affect health outcomes. Longitudinal cohort studies (e.g., ABCD Study, Dunedin Study) provide stronger evidence than cross-sectional surveys by following participants over time.
Related Terms
More in Research Methods
Randomized Controlled Trial (RCT)
The gold standard study design in clinical research. Participants are randomly assigned to treatment or control groups to minimize bias and establish causation.
Systematic Review
A structured synthesis of all available evidence on a specific research question, using predefined criteria to identify, evaluate, and summarize studies.
Meta-Analysis
A statistical technique that combines quantitative data from multiple studies to produce a pooled estimate of effect size with greater statistical power than any individual study.
Placebo-Controlled
A study design in which the control group receives an inert substance (placebo) identical in appearance to the active treatment, to account for the placebo effect.
Bioavailability
The fraction of an administered dose that reaches systemic circulation in an active form. Varies substantially by route of administration for cannabinoids.