Contrary to common belief, randomised controlled trials inevitably produce biased results

Much of the social and medical sciences depend on randomised control trials. But while this may be considered the foundational experimental method, a certain degree of bias inevitably arises in any trial; whether this is sample bias, selection bias, or measurement bias. This is important as the level of validity of a trial's causal claims can be a matter of life or death. To Alexander Krauss, the scientific process is a complex human process, involving many actors required to take many unique decisions at many different stages, and so some degree of bias is unavoidable. This has implications for the reproducibility crisis, as variation between study outcomes becomes the norm, and one-to-one replication is not possible.