9 Are randomised controlled trials ethical?
Randomized experiments—long the gold standard in medicine—are increasingly used throughout the social sciences and professions to evaluate business products and services, government programs, education and health policies, and global aid. We find robust evidence—across 16 studies of 5,873 participants from three populations spanning nine domains—that people often approve of untested policies or treatments (A or B) being universally implemented but disapprove of randomized experiments (A/B tests) to determine which of those policies or treatments is superior. This effect persists even when there is no reason to prefer A to B and even when recipients are treated unequally and randomly in all conditions (A, B, and A/B). This experimentation aversion may be an important barrier to evidence-based practice.
Meyer et al. (2019)
Is it ethical to withhold an intervention that may benefit someone by assigning them to a control group?
A common response to this question is that this effectively already occurs in many instances without trials:
- Interventions are often piloted, which is equivalent to excluding a group of people who could benefit.
- Interventions are often scaled up, meaning that it takes time for everyone to receive the intervention.
A randomised controlled trial might be considered more ethical than either of those scenarios as it is similarly a phased introduction, but with a mechanism to determine its effectiveness and improve future outcomes. Absent a robust test, we need to be clear about the limits of our knowledge. There are many cases where an intervention assumed to be helpful was later found to be ineffective or harmful.
Further, trials often have protocols that in the case of large early effects indicating success or harm, they can be ceased or implemented more rapidly.
Another related question is whether it is fair to experiment on people at all. Don’t we risk harm?
One response is that every time you roll out a new program, product, communication or tool that may change behaviour or affect their wellbeing, you are running an experiment. It’s just that if you’re doing it absent a control group or some other mechanism to determine effectiveness, your experiment does not even have the benefit of enabling you to know whether it works, or is helping or harming people.