Categories → Causal Inference , Statistics , Study Design
Randomized Controlled Trials (RCTs) are a type of experiment in which individuals are randomly assigned to either a treatment group or a control group.
The treatment group receives the intervention, while the control group does not. The two groups are then compared to determine whether the intervention had an effect.
RCTs are considered the gold standard for experiment design because they can establish causality between the intervention and the outcome. This is because randomization ensures that the treatment and control groups are similar in all relevant aspects except for the intervention, so any differences in outcome between the groups can be attributed to the intervention. Additionally, blinding can be used to reduce bias, as neither the participants nor the researchers know who is in the treatment or control group.
However, RCTs can deliver inaccurate estimates of a causal effect if sample is biased, or if the result is inappropriately generalised to a larger group. The result may also have occurred due to chance.
RCTs are not always feasible or ethical, especially when the intervention being tested has potential risks (including to the participants!) or is costly, or impractical. In such cases, non-interventional or observational studies can be used to study causal relationships. These types of studies do not involve randomization, but instead, researchers try to control for potential confounding variables through study design and statistical analysis. This latter approach is used in Causal Wizard.
To obtain causal results from non-interventional or observational studies, researchers can use techniques such as propensity score matching or instrumental variables analysis, both available in Causal Wizard. Propensity score matching attempts to balance the treatment and control groups based on observed characteristics that may influence the outcome, while instrumental variables analysis uses natural experiments or other variables that are related to the intervention but not the outcome, to estimate the causal effect.
Overall, RCTs are considered the gold standard for establishing causality, but non-interventional or observational studies can also provide valuable insights into causal relationships when RCTs are not feasible or ethical.