The next step in ensuring your AB test or experiment runs smoothly and ethically is making sure you understand local and federal regulations around conducting research experiments on humans..In the US, these regulations have been outlined above..The regulations mainly look at: Informed consent, with a full explanation of any potential risks to the subject..Providing additional safeguards for vulnerable populations such as children, mentally disabled people, mentally ill people, economically disadvantaged people, pregnant women, and so on..Government-funded experiments need the approval of Institutional Review Board or an independent ethics committee before conducting experiments..During the AB test or experiment, it’s also a good idea to regularly check-in and see how your subjects are responding to the treatments, not only for the purpose of scientific research, but also to quickly solve any health or well-being issues..This could be in the form of a short popup survey or email to check if the user is safe and well, or face to face consulting..Also, having an opt-out option allows the subject to take control if they feel their health or well-being is at risk..Having some people opt-out might seem inconvenient for your study, but a serious or tragic incident as a result of a participant having to go through the full course of the treatment is a far worse outcome..Observational studies might be a good alternative if the above steps are in no way feasible for your experiment..Observational studies are limited when making conclusions, and only real experiments allow you to make confident conclusions from the data..However, in some situations, it is not possible nor ethical to force treatments onto subjects.. More details