The three levels of controlled experiments
In science, we have three different meanings for the term controlled experiments.
- controlled extraneous variables: control everything
- controlled groups: groups with treatment compared to groups without treatment
- controlled treatments: more like an exploration of the treatment since each subject receives different treatments
Controlled group is trying to eliminate the effect of uncontrolled variables by using the randomness in each group.
Lei Ma (2018). 'Controlled Experiments', Datumorphism, 12 April. Available at: https://datumorphism.leima.is/til/statistics/controlled-experiments/.