قارن الطرق

	اختبار الدواء الوهمي لتأثيرات المعالجة غير المتجانسة	الفرق في الفروق (Diff-in-Diff)
المجال	الاستدلال السببي	الاقتصاد القياسي
العائلة	Regression model	Regression model
سنة النشأة	2000s–2010s	1994
صاحب الطريقة	Rosenbaum (placebo test concept); Athey & Imbens (HTE estimation framework)	Card & Krueger (canonical 1994 application); Angrist & Pischke (textbook treatment)
النوع	Validation / falsification test	Causal inference / panel regression
المصدر التأسيسي	Imbens, G. W., & Rubin, D. B. (2015). Causal Inference for Statistics, Social, and Biomedical Sciences: An Introduction. Cambridge University Press. ISBN: 978-0521885881	Angrist, J. D., & Pischke, J.-S. (2009). Mostly Harmless Econometrics: An Empiricist's Companion. Princeton University Press. ISBN: 978-0691120355
الأسماء البديلة	HTE placebo test, heterogeneous-effect placebo check, subgroup placebo test, CATE placebo validation	diff-in-diff, DiD, Farkların Farkı (Diff-in-Diff)
ذات صلة	3	5
الملخص	A placebo test for heterogeneous treatment effects is a falsification strategy used to validate whether estimated variation in treatment effects across subgroups or covariate values is genuine rather than an artifact of model specification, overfitting, or coincidental patterns. By applying the same estimation procedure to pseudo-treatments, fake outcomes, or subgroups that logically should not differ, researchers check that observed heterogeneity reflects real causal variation.	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.