Observational and real-world studies

While randomized studies provide the best evidence, they are not practical in some circumstances, for example rare diseases. Observational and real-world studies cannot replace randomized trials but they provide evidence of causality to be interpreted with other data. Observational studies are of two types – descriptive and analytical. Observational and real-world studies suffer from several biases, mainly selection bias. This is hard to overcome, but can be mitigated by the use of propensity analysis and sensitivity analysis.