Given their intrinsic methodological limitations, including lack of statistical sampling, case reports are placed at the foot of the hierarchy of clinical evidence, together with case series. Nevertheless, case reports do have genuinely useful roles in medical research and evidence-based medicine.
A case-control study, like other medical research, can help scientists find new medications and treatments. Find out how 'cases' are compared with 'controls' in this type of study. This type of study is a relatively quick and easy way to find evidence, but it has scientific limitations.
They can be prospective studies and gather data going forward, or retrospective cohort studies, which look at data already collected. The Nurses' Health Study is one example of a large cohort study, and it has produced many important links between lifestyle choices and health by following hundreds of thousands of women across North America.
Video: Cross-Sectional Research: Definition & Examples Cross-sectional research is used to examine one variable in different groups that are similar in all other characteristics. Learn more about cross-sectional research in this lesson and test your knowledge with a quiz at the end.
Meta-analysis in clinical trials. DerSimonian R, Laird N. Comment in BMJ. 2016 May 04;353:i2156. This paper examines eight published reviews each reporting results from several related trials. Each review pools the results from the relevant trials in order to evaluate the efficacy of a certain treatment for a specified medical condition.
Systematic review and meta-analysis of clinical trials of the effects of low carbohydrate diets on cardiovascular risk factors. Santos FL(1), Esteves SS, da Costa Pereira A, Yancy WS Jr, Nunes JP. Author information: (1)Centro Hospitalar Vila Nova Gaia/Espinho, Gaia, Portugal Centro Hospitalar do Porto, Porto, Portugal.