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	Placebo Test di Valutazione delle Politiche	Difference-in-Differences (Diff-in-Diff)
Campo	Inferenza causale	Econometria
Famiglia	Regression model	Regression model
Anno di origine	1990s–2000s	1994
Ideatore	Bertrand, Duflo & Mullainathan (2004 canonical formalization); Imbens & Wooldridge (2009 textbook treatment)	Card & Krueger (canonical 1994 application); Angrist & Pischke (textbook treatment)
Tipo	Falsification / specification check	Causal inference / panel regression
Fonte seminale	Imbens, G. W., & Wooldridge, J. M. (2009). Recent Developments in the Econometrics of Program Evaluation. Journal of Economic Literature, 47(1), 5-86.	Angrist, J. D., & Pischke, J.-S. (2009). Mostly Harmless Econometrics: An Empiricist's Companion. Princeton University Press. ISBN: 978-0691120355
Alias	placebo test, falsification test, fake treatment test, placebo regression	diff-in-diff, DiD, Farkların Farkı (Diff-in-Diff)
Correlati	4	5
Sintesi	A policy evaluation placebo test is a falsification check used in quasi-experimental research to validate a causal identification strategy. The researcher applies the same estimation method to a pseudo-treatment — a time period, group, or outcome where the real policy could not have had an effect — and checks that no spurious effect is detected. A null placebo result builds confidence that the main estimate reflects a genuine causal impact rather than bias or confounding.	Difference-in-Differences is a causal-inference method that estimates the effect of an intervention by comparing how a treatment group and a control group change over time. Made famous by Card and Krueger's 1994 minimum-wage study and developed in Angrist and Pischke's Mostly Harmless Econometrics, it isolates the treatment effect as the difference between the two groups' before-after changes.