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Difference-in-differences

The difference-in-differences method measures the effect of a policy by comparing the changes in an affected group with those in an unaffected group. It examines the differences in both groups before and after the policy was implemented. This approach makes it possible to isolate the impact of the policy under study more precisely. It is particularly useful when randomised trials are not feasible. The double-difference method is widely used to evaluate public reforms or social programmes.

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Last modified: July 27, 2026