A policy change creates variation like random assignment, used to estimate causal effects without randomization.

• A. Gold Standard
• B. Natural Experiment
• C. Empirical Research
• D. Research Question

Answer: (B)

When you want to estimate causal effects without randomization, you look for sources of variation that act like random assignment. A policy change that affects some groups but not others can create this kind of variation, allowing you to compare outcomes across those exposed and unexposed as if the treatment were randomly assigned. This is a natural experiment.

This approach is different from the ideal gold standard, which is a randomized controlled trial where assignment to treatment is truly random. Natural experiments are practical when randomization isn’t feasible, using real-world policy-induced differences to identify causal effects.

Empirical research is a broad activity that includes collecting and analyzing data, but it doesn’t by itself guarantee causal identification, whereas a natural experiment provides a concrete strategy for attributing differences in outcomes to the policy-induced treatment.

A research question is about what you want to investigate, not the method used to identify causal effects.