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With appropriate control of other factors related to lung cancer and smoking status, such as gender and age, observational studies have shown a strong association between smoking and lung cancer events. Observational studies can also help inform probable cause and effect associations before randomised data are available, as randomised controlled trials often take years to complete. Additionally, observational studies help researchers know what happens in real life situations.
These studies serve as a collection of data from standard practice. In conclusion, observational studies are a key part of research. They help to investigate relationships that are unable to be tested under randomised controlled experiments, can help provide insight and develop hypotheses on what subsequent randomised evidence is needed for future research, and can provide an understanding on how things work in clinical practice. The strengths and weaknesses of a study design should be seen in light of the kind of question the study sets out to answer.
Sometimes, observational studies are the only way researchers can explore certain questions. For example, it would be unethical to design a randomized controlled trial deliberately exposing workers to a potentially harmful situation. If a health problem is a rare condition, a case control study which begins with the existing cases may be the most efficient way to identify potential causes.
Or, if little is known about how a problem develops over time, a cohort study may be the best design. However, the results of observational studies are, by their nature, open to dispute. They run the risk of containing confounding biases. But the link may be explained by the fact that people who meditate also exercise more and follow healthier diets. In other words, although a cohort is defined by one common characteristic or exposure, they may also share other characteristics that affect the outcome.
Such research is time-consuming and expensive — it may take years before results are available.
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